Digitized by the Internet Archive in 2017 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/descriptivecatal00andr_0 CATAI, Tl'iRTlAK^Y VI'^HT h'AYIJM FRONTISPIECE -Vuir' ln- APCiNciTHRRiiiM SIAIE GEOLOGICAL SURVEY, /\ DESCRIPTIVE CATAEOCIIE OF THE TERTIARY VERTERRATA OF THE FAYUM, EGYPT. BASED ON THE COLLECTION OF THE EGYPTIAN GOVERNMENT IN THE GEOLOGICAL MUSEUM, CAIRO, AND ON THE COLLECTION IN THE BRITISH MUSEUM (NATURAL HISTORY), LONDON. EY CHAKLES WILLIAM ANDREWS, D.Sc. LONDON: PRINTED BY ORDER OF THE TRUSTEES OF THE BRITISH MUSEUM. SOLD BY LONGMANS & Co., 39 PATERNOSTER ROW, E.C. ; B. QUARITCH, 15 PICCADILLY, W. ; DULAU & Co., 37 SOHO SQUARE, W.; KEGAN PAUL & Co., 43 GERRARD STREET, W. ; AND AT THE BRITISH MUSEUM (NATURAL HISTORY), CROMWELL ROAD, S.W. 1906. {All rights reserved.) PUINTED BY TAYLOR AND FRANCIS, RKD LION COURT, FLEKT STREET. S Cd G PREFACE. xImong recent discoveries in Palaeontology, none have excited more interest than the Lower Tertiary Vertebrate Faunas of the Fayum. They add so much to our knowledge of the primitive Mammalia, especially of the Hyracoidea, Proboscidea, Sirenia, and Cetacea, that an exhaustive account of them, so far as discovered, has become essential. The Trustees of the British Museum have therefore availed themselves of the generous co-operation of the Egyptian Government to produce a Descriptive Catalogue of all the more important fossils by which these ancient Faunas are at present known. The greater part of the collection, now in the Geological Museum, Cairo, was made by Mr. H. J. L. Beadnell under the direction of Captain H. G. Lyons, Director-General of the Egyptian Surveys ; while the smaller collection, in the Geological Department of the British Museum, was made partly by Dr. C. W. Andrews, the author of this Descriptive Catalogue, partly by donations of duplicates from the Egyptian Government. During the preparation of the work Dr. Andrews has had the opportunity of studying both these collections in detail, and the result is a satisfactory basis for future research. How much remains to be discovered for the elaboration of the preliminary sketch now given, will be readily realised on perusing the various sections of the Catalogue. Thanks are due to the Right Hon. the Earl of Cromer, G.C.B., for his sympathetic interest, and to Captain Lyons for his cordial help and successful negotiation with the Egyptian Government. The Trustees of the British Museum are also indebted to Captain Lyons and Mr. Beadnell for their assistance to Dr. Andrews in his collecting expeditions ; while special acknowledgment must be made of the funds generously provided for some of these expeditions by Mr. W. E. de Winton, whose presents are severally enumerated in the Catalogue. A. SMITH WOODWARD. Depaetment of Geology, Beitish Museum (Natueal Histoey). 5th March, 1906. b I if# INTRODUCTION. The Fayum *, the lake province of Egypt, is a district occupying a depression in the desert to the west of tlie Nile Valley opposite Wasta, a small town about fifty-seven miles south of Cairo. This depression, which is roughly circular in outline, is separated from the river-valley by a belt of desert varying in width from about a mile and a half to some six or seven miles, and crossed at one point by a canal, the Bahr-el-Yusef, which runs through a narrow strip of low ground and is practically the only source of water-supply for the Avhole district. The water thus brouglit in from the Nile is distributed by irrigation-canals to the cultivated part of the district, and the surplus eventually finds its way through a number of channels, some of which form picturesque gorges, to the lowest part of the de])ression, occupied by a large expanse of brackish water, the Birket-el-Qurun. This lake is about twenty-five miles long, with a maximum width of only six miles ; it is very shallow, the maximum depth at present being about sixteen or seventeen feet, and its shores in most places are very low and gently sloping. In Pleistocene times the floor of the depression was occupied by a body of water of vastly greater area than the present lake, evidences of its former extent being found in the widely spread lacustrine deposits, chiefly clays, containing, in addition to numerous Mollusea, remains of Elephas africanus. Hippopotamus, Buhalis, Canis, together with those of Crocodiles, Chelonians, and Fishes (8) f. In one or two places also numerous * Tlie following sketcli of the Topography and Geology of the Tayuni is mainly founded on Mr. II. J. L. Beadnell’s detailed report. The Tojiography and Geology of the I’ayiun Province of Egypt (Cairo, 1005), which should be consulted for further information. The jiapers by Elanckenhorn, mentioned in the list on p. x.\x, are also of great importance. t The numbers within brackets refer to the list of ])ublications on p. xxix. h Geological jMap or the Faau.m Depeessiox (taken from pi. x\ii. of IT. J. L. BeadneH’s Report on the Topography and Geology of the Tayuin Troiince : Survey Dept., Cairo, lOOo). The crosses mark some of the cliief localities from which Upper Eocene Vertebrates have been collected. Heights are given in metres. INTRODUCTION. 1^’TR0DUCTI0X. vii stumps of trees of considerable size occur, indicating that in some parts, at least, in the neiglihourliood of the water the country was wooded. Later, within the historic })eriod (XII. Dynasty, hcgiiining about 2778 b.c.*), the lake was converted into an artificially-controlled reservoir, Tjakc Mocris, and was employed to regulate the su])ply of water in years of exce[)tionally high or low Nile floods. At this date, though smaller than the earlier Pleistocene lake, the water-covered area was far greater than at the present time, indications of its former extent being found in old shore-lines, still fringed with the stumps of tamarisk-bushes, and in the ruins of temples and cities {e.g. Qasr-el-Sagha). These remains are now separated from the water by miles of desert. Later still, probably in Ptolemaic times, the lake ceased to be used as a reservoir, and the quantity of water admitted to the Fayum was limited, so far as possible, to the amount actually required for the irrigation of the district. The consequence of this was that the lake received only such surplus water as drained from the cultivated lands, and its level began to fall until, within the last year or two, it reached its smallest dimensions. Since then the more abundant supply of water resulting from the vast irrigation-works in the Nile Valley has led to a considerable area being reclaimed, and the consequent increase in the amount of water draining into the lake has brought about a slight rise in its level. The cultivated laud lies to the south and east of the lake, while on the north the desert extends down almost to the water’s edge, from which it is separated by a belt of sand-dunes and swamp of varying Avidth, covered with scanty vegetation, consisting mainly of tamarisk and reeds. Along the Avhole of the north margin also there is a band of lacustrine deposits Avidening out towards the east. These beds overlap the edge of the Middle Eocene strata Avhich form the loAver parts of the depression. With only one or two exceptions, the Avhole of the vertebrate remains described in the present volume are derived from the Middle and Upper Eocene deposits lying on the northern side of the lake, and it will only be necessary here to give a brief account of the geological structure of that region. Looking nortliAvards from a suitable point of vicAv on the southern side of the lake, the northern slope of the depression can be seen rising in a series of escarpments of varying height (see Map and Section), and running roughly parallel to one another from about E.N.E. to W.S.W. ; the terraces betAveen the successive steps vary in AAudth from mere ledges to plains some kilometres Avide. There are three main escarpments, of Avhicli the * Flinders Petrie, ‘A Historyof Egypt,’ vol. i. p. 147. Jj 2 rNTRODUCTrON. viii lowest is best (levelo])e(l towards tlie western end of the lake, running parallel with and at a short distanee from the northern shore ; this is composed of Kavine beds, Birket- el-Qnrun series, and the lower part of the (iasr-el-Sagha beds. The Kavine beds are, for the most part, obscured by the overlying lacustrine deposits. The next main escarpment is seen rising very steeply in the middle ‘distance ; it is composed of the higher beds of the Qasr-el-Sagha series. To the north of this, and separated from it by a succession of broad terraces some kilometres wide, is the magnificent range of cliffs, the Jebel-el-Qatrani, composed of the upper beds of the Fluvio-marine (Upper ISI Widan e! Faras. Summit of J clQatrani . JfC Qasr e! Sag ha 2,5 Dime S. Surface of ancient Lake M a? ns, 22-25 m. above, present sea level. Sea Level Horizontal Sea lei. — ^ ^ ^ ikiiometres. Heights ui metres above sea tevef. Skctiox (from north to south) showing the succession of beds on the nortli of Eirket-el-Qurun. (Reduced from part of the section on pi. xxii. of H. J. L. Beadnell’s Eeport on the Topography and Geology of the Rayum Province : Survey Dept., Cairo, 1905.) a. Lacustrine clays ; 2. Lower Gligocene ; 3. Interbedded basalt sheet ; 4. Upper Eocene (Eluvio-marine) ; 5. Qasr-el-Sagha series; 6. Birket-el-Qurun series ; 7. Ravine Beds. Eocene) series, and capped by a thick bed of basalt, which Mr. Beadnell regards as occurring at the junction of the Eocene and Oligocene beds. This upper range of cliffs practically marks the northern edge of the depression, and beyond it comes the high undulating plateau of brown ])ebble-strewn desert, composed mainly of flnviatile beds of Oligocene age, in which so far no vertebrate remains have been found, 'riiroughout the whole series the beds dip very gently (2° or 3°) towards the north, and have been subjected to very little fruiting or other disturbance. The following Table show’s the succession of strata composing the country to the north of the lake, together with a list of the vertebrate remains at present known from the various horizons : — TXTHODUCTrON. IX Tabli-: siiOAViNO Succession and Cbassieication oe Sthata in the. Fayum. (Slightly nioclillccl li-om tlie Titblo given Iiy Mr. Bendnoll in his Report on the Topography and Oeology of Eayi'un Province, pp. Bl-.'l.j.) Approximate average thickness in metres, north par ot'Eayilni. RECENT Alhivial soil, clays, sands, &e. and Blown sand. PLEISTOCENE. Lacustrine clays extending to 23 metres above sea-level (d in Section). MIDDLE PLIOCENE. Gravel terraces (? Pleistocene). 50 Sbell-boring on rock-surfaces. Eossiliferous deposits of Sidinant. LOWER OLIGOCENE. Tongrian. 30 Fluvio-marine Beds (Jehel-el-Qatrcmi Beds). — Sandstones and sandstone-grits witli silicilied trees. (2 in Section.) Basalt Sheets, interbedded and contemporaneous. (3 in Section.) UPPER > EOCENE. Bartonian. 1 250 Fluvio-marine Series (4 in Section). — A'ariegated sands, sandstones, clays, and marls, with limestone-grits and thin bands of limestone. In the lower beds of this Series are large numbers of silicilied trees associated with vertebrate remains, including; — Arsinoitherium zitieh, A. andrewsi, Saiihatlierium antiquum, S. minus, S. maqnuni, S. majus, M eyalohijrux eoccenus, M. minor, Palceomastodon headmelli, P. u’intoni, P. jiarvus, P. minor, Mceritherium (?) Ijonsi, M. trigonodon, Phiomia serridens, Ancodon gorringei, A. parvus, A. sp., Bhagatlierium mjgpiiacum, Geniohifus minis, G. -fajvmensis, G. major, llya-nodon sp., Pterodon africauus, Apierodon macrognathus, Sinopa ethiopica, Eremopezus eocanius, Crocodilus articeps, 0. megarhinus, Tomistoma gavialoides, Testudo amnion, T. htadnelli, T. isis, Stereogenijs lihyca, Podocnemis fajumensis, P. blanckenhorni with var. ovatu, Pelo- rnedusa progaleata, Aetobatis sp. Upper Mokattam. 155 Qasr-el-Sagha Series {Carolia Beds) (5 in Section). — Alternating limestones, marls, clays, and sandstones. The vertebrate remains include :: — Mceritherium, lyonsi, M. gracile, Burytherium grave, Eosiren libyca, Zeuglodon osBis, Crocodilus S]).. Tomistoma africanurn, Pseqdioptliorus eocienus, Thalassochelys libyca, Podocnemis antiqua, P. stromeri and var. major, Stereogenijs cromeri, S. padocnemioides, Gigantoqihis garstini, Pterosphenus schweinfurthi, Fajumia schweinf urthi,Socnop)a;a grandis, Pristis fajumensis, P. ingens, Euqiristis reinachi, Propirisiis schweinfurthi, Mi/liobatis sp., Carcharodon sp. MIDDLE EOCENE. Parisian. << H o O 5U Birlcet-el-Qurun Series (^Opierculina-Nummulite Beds) (G in Section). — Sandstones and clays, with sandy limestones and one or more well-marked concretionary sandstones weathering into large globular masses. The chief vertebrate fossils are : — -Eocetus schweinfurthi, Prozeuglodon atrox, and (?) Zeuglodon isis, Tomistoma herunense, Saurocephcdus fajumensis, Enchodus sp., Coelorhynchus sp., Progym- nodon hilgendorJi,iiVo\yijtQv'u\ tish, Oxyrhina spp., '1 Alopecias sp., Lamna verticalis, L. sp., (?) Odontaspiis aschersoni, Odontaspis spp., Carcharodon sp., Jlemipristis curvatus, Galeocerdo cegyptiacus, Alopiiopsis sp., Aprionodon frequens, Priono- don sp., Carcharias spp., Propristis schiveinfurlhi, (?) Eopristis reinachi, Amblypristis clieops, Myliobatis latidens, M. fraasi, M. dixoni, M. acutus, M. oweni, M. spp. - 70 Ravine Beds (7 in Section). — AUhite marls and marly limestones with remains of large Zeuglodous and scales and teeth of fishes. 130 WadiRayan Series {Namniulites gizehensis Beds). — Limestones, inarls, clays, vfec. X 1NTK0])UCT10N. ]‘'roin tills 'rable it will bo gatberod that, speaking generally, from earlier to later times the strata of the Fayfim were deposited nearer and nearer to some land-mass. In the early Ikicene the presence of thick marine liods far to the southwards shows that the shores of the Ethiopian continent were still remote from the area now under discussion ; and this state of things seems to have continued till the Middle Eocene, as shown by the thick uummulitic beds of the Wadi Ilayan series, and the exclusively marine character of the fossils both of those beds, the Eavine beds, and the Birket-el- (Jurun scries above. In the Qasr-ol-Sagha series, on the other hand, there is much evidence that the shore was not far off, the presence of thick beds of clay, often current-bedded and containing numerous impressions of leaves, as well as the occurrence of land-mammals pointing to this conclusion. In fact, the deposits at this horizon may be regarded as partly marine and partly littoral, there having been many small oscillations of level. In the Fluvio-marine (Upper Eocene) beds above, the near presence of a largo land-mass is still more obvious, these deposits being, in fact, almost entirely fiuviatile, and probably representing the remains of the delta of a great river which Mr. Beadnell, for various reasons, considers flowed from the south-west At or near the end of the Eocene period this state of things was interrupted by an outburst of volcanic activity, which gave rise to the interbedded basalt-sheets of the Jebel-el-Qatrani (see Map) ; but after this the fiuviatile conditions were again resumed and appear to have continued with some interruptions throughout the Oligocene, Miocene, and, in ]mrt at least, the Pliocene periods. Throughout this vast epoch there seems to have been a general tendency towards a gradual advance of the coast-line northwards, and such interruptions and oscillations as did occur are marked by the presence of interbedded marine, littoral, and perhaps, in a few cases, lacustrine deposits. This long series of Eluvio-marine beds offers just the conditions necessary for the preservation of a succession of vertebrate faunas, and, in fact, these have already been found at two horizons in addition to the Eocene beds 'with wdiich this Catalogue is mainly concerned, namely, in the Lower Miocene and the Middle Pliocene. So long ago as about 1898, Dr. Blanckenhorn discovered remains of a Khinoceros and of an Anthracotheroid Mammal [Brachyodiis afneanus), together with other vertebrate fossils, in the Lower Miocene beds of Mogara, which lies to the north-west of the Fayum about five days’ march. This collection was afterwards described by the present writer (4, 5j, who later, with the late Mr. Barron of the Egyptian Survey, revisited the locality, where they obtained, in addition to the forms already known, remains of * ‘ deport oil the hhivuin Province,’ p. OG. INTRODUCTION. XI a Proboscidean closely allied to, if not identical with, Tetralclodoii angustidens, remains of which occur in beds of the same age in Europe. Mr. Beadnell also has lately made a collection from the same place, but this has not yet been fully examined, and quite recently Dr. Stromer (45) has described some vertebrate remains from the same horizon in the Wadi Faregh, which lies to the north of the Fayum. To the north of this, again, in the Wadi Natrun, a considerable number of vertebrate remains of Middle Pliocene age have been collected by Captain Lyons, Mr. Beadnell, and, still more recently, by Drs. Stromer and Blanckenhorn. These have been described by Studer (46), Stromer (37, 45), and the present writer (7), and include such forms as llipparion aff. gracile. Hippopotamus Idpponensis, Sus sp., Ilippotragus cordieri, Lihgtlicrium or Samotherium sp.. Mastodon sp., as well as remains of Carnivora belonging to the Canidm, Lutrinae, Phocidae, and Macliaerodontinse. There are also traces of a Sireniau and of a llodent, probably a species of OnjctoJagus. It is thus clear that in a north- and-south line from the Fayum we already know such a succession of faunas as might be expected to occur in such a series of deposits, and it is at least probable that further careful search of this region may lead to the discovery of others of intermediate age which will throw further light on the history of several groups. For instance, it seems very likely that remains of annectant forms between the Zeuglodonts and Odontoceti and between the Anthracotheriidm and the Hippopotamidm are entombed in these beds. The first vertebrate fossils discovered in the Fayum were collected by Schweinfurth (35) in 1879 on the island Geziret-el-Qorn (see Map), where, in beds of the Birket- el-Qurun series, he obtained remains of Zeuglodons and fishes belonging to the genera Myliohatis, Propristis, Ilemipristis, Corax, Galeocerdo, Carcharias, Carcharodon, Otodus, Lamna {Odontaspis), Saurocephalus, {V)Enchodus, and Progymnodon : this collection was afterwards described by Dames (25). In the winter of 1885-G the same traveller visited the escarpments to the north of the lake, and from the cliffs over Qasr-el-Sagha (Schweinfurth’s Temple) collected other remains of Zeuglodon, including the mandibular ramus afterwards described by Dames (27) under the name Zeuglodon osiris. Nothing further was done until, in 1898, Mr. Beadnell commenced a survey of the depression and collected numerous remains of Fishes and Crocodiles, and noticed that fragments of bone were common on certain horizons, but nothing of particular interest was obtained. In April, 1901, the present writer had an opportunity of visiting the district with Mr. Beadnell, on which occasion a considerable number of vertebrate remains, including portions of the skeletons of Mceritherium, Eosiren, INTRODUCTION. xii (/ if/ai/foj)h/s. See., wcic collected from the Middle Eocene beds, and it was arranged 1o rc'visit the district for the ])urpose of obtaining further material. This was done, and r('snlt('d not only in the collection of much that was new from the Middle Eocene ('scar))ment, hut also in the discovery that the Eluvio-maiine beds above were bone- Ix'ai'ing and in the finding of the first traces of Palceomastod on . Towards the end of the same year Mr. Beadnell returned to the district and paid special attention to the Iduvio-marine beds, from which he obtained the first remains of Arsinoitherium, as well as of other new mammals and reptiles ; he was also fortunate in tinding a spot Avhere bones occur in considerable numbers in a limited area, instead of being widely scattered as is usually the case in these deposits. His expeditions in the Avinters of lOOll-o, 1903--4, residted in the accumulation of a very large mass of material (only part of Avhich is here catalogued) in the Geological Museum at Cairo. During the springs of 1902 and 1903 the present Avriter also collected in the same district, and obtained a considerable number of specimens, including several ncAv forms. Lately Baron E. Nopesa visited the Eayiim and made a collection of vertebrate remains, including some good specimens Avhich he presented to the British Museum : these are referred to in the present Catalogue. In the early part of 1902, I)rs. Stromer and Blanckenhorn also made a sliort stay in the district, and their collections of Aertehrate fossils have been in part described: the Zeuglodonts (38, 40, 41) and fish-remains (43, 44) by Dr. Stromer himself; the Chelonians by Dr. lleinach (34); Avhile Dr. O. Abel is preparing a memoir on the Sirenia, including also the earlier forms from the Mokattam Hills (see also i). The collections of remains noAv preserved in the British Museum aud in the Geological INluseum at Cairo comprise representatives of all the main divisions of the vertebrate phylum except the Amphibia. Both in point of numbers and interest, the Mammals are by far the inost important ; next to these come the Ileptiles, Avhile the Birds are reju’esented by mere fragments of a single species. The Mammals may be divided into throe sections : — (1) the land-mammals Avhich seem to be truly endemic to the Etlho])ian region ; these occur Ijoth in the Ujiper and Middle Eocene beds, and include such genera as MoerUhcrinnf, ]\da’oniasto(lon, ArsinoifJienvtn, Jlaryihcyivnn, Megaloliyya.v, iSr/f/Iiatheyiiun, and ])erhaps Geniohyus: (2) forms of Avhich close allies occur in other regions in approximately contem})orary deposits; these, so far as at present knoAvn, occur only in the Upper Eocene beds, and include such genera as Ancodon, Jdnu/at/iey/nin, J/ywiiodon, lieyodon, Aplerodon, and Siiwj)a : (3) the acpiatic mammals so far not found in tlie Upper Eocene beds, INTRO DUCT I ox. xiii and cnni])risin" Eosiren, Zeiiglodon, and Erozeucjlodon. It seeins probable tliat some of these last, like the genera included in section 1, are of endemic origin, having originated from land-mammals inhabiting the region. In the first section it will be noticed that all the genera belong to the Ungulata, and with one exception to that subdivision of the order to which the name Subnngulata has been given — a group in which the feet have not undergone any extreme s])ecialisation. The exception to this is Geniohyus, which is an Artiodactyl and should perhaps be placed in the second section. Among the Subungulates, by far the most striking of the new forms is Arsinoitheriurn, the first remains of which were found by Mr. Beadnell towards the end of 1900. Subsequently a great quantity of remains of one of the species, A. zitteli, were collected, including skulls of various ages, and nearly all the other parts of the skeleton (see text-fig. 3G, p. GO), so that the structure of this extraordinary mammal is now almost completely known, so far as this is possible from the bones alone. In its general appearance Arsinoitherinm zitteli must have been somewhat like a large and heavily built Ehinoceros (see p. xxviii) : op the head there were two pairs of horns, the great anterior nasal horns projecting forwards and upwards, and a much smaller pair situated over the orbits. Both these horns, unlike those of Ehinoceros, are bony out- growths of the skull, but most likely the anterior pair at least were covered with horny sheaths, much like those of the Cavicorn Iluminants. The muzzle was very narrow, so that probably the animal did not graze, but browsed on low bushes and herbage, grasping its food by means either of a prehensile tongue or possibly of a mobile upper lip. In correlation with the great weight of the skull, the occipital condyles are large and the ridges for the attachment of muscles prominent ; from the form of the occipital condyles and the forward slope of the occipital surface, it appears that the head could be moved freely up and down. The dentition is complete, and the teeth, Avhich form closed series on either side of both the upper and lower jaws, possess extraordinarily high crowns, especially for an animal of such an early period. The molars, which differ very widely from the premolars, consist of two very high transverse crests, and it is very difficult to imagine from what type of low-crowned tooth they Avere derived ; it is, however, possible that they may have originated from a tooth resembling the molars of the Hyracoidea, in Avhich a gradual increase in the height of the croAvn has been accompanied by the infolding of the outer Avail till the crown is divided into an anterior and a posterior column. The possibility that Arsiuoithcriida* may have been descended from the same ancestral stock as the Hyracoidea is supported c XIV INTRODUCTION. by some resemblances of the structure of the skull and by the flict that both groups originated in the Ethiopian region. In the skeleton the chief characteristic is the massiveness of all the bones, a jieculiarity that no doubt has had much to do with f heir ])rescrvation in such large numbers, while the much more lightly constructed limb-bones of Palceomastodon are extremely rare. The neck was very short and thick, ihe posterior cervical vertebrae being much like those of Elephas. The limbs are extraordinarily massive ; the fore limb is a little the shorter and was probably bowed slightly outwards. The feet are pentadactyl ; the fore foot is very similar to that of the Proboscidca, the rdna taking an even greater share in the formation of the carpal joint, so that the bones of the proximal row tend to overlap those of the distal row ])reaxially. In the hind foot the astragalus articulates distall y with both the navicular and cuboid as in the Amblypoda, not with the navicular alone as in the Proboscidca. The relationships of ArshioUherium are very doubtful, and it so far differs from all other Ungulates that a new suborder, the Barypoda has been founded for its reception. It is a highly specialised form, of which the ancestors are quite unknown; possibly, as suggested above, it may have originated from the same group which gave rise to the Hyracoidea, and through this primitive stock may be related to some of the early, perhaps pre-Tertiary, South-American types : this possibility will be referred to again below. The Hyracoidea are an extremely isolated and in some ways very primitive group : previous to the discovery of these Egyptian members of the suborder, no fossil representatives were known, at least in the Old World, except Pliohjrax from the Lower Pliocene of Samos and Pikermi. The genera Sagliatherium and 3Iegaluhgrax now described from the Upper Eocene of the Eayum throw little or no light on the history of the group : they are more primitive only in having the incisors and canines all present in the adult, and the premolars all simpler than the molars ; otherwise, as in the peculiar modiffcation of the anterior incisors, they are much like the recent forms. The considerable number of species together with the large size of some of them show that in the Upper Eocene ])eriod they were an important factor in the fauna of the Ethiopian region, to which the group seems to bo endemic. Of their relationshi])s little is knowm : Ameghino has described as Ilyracoids a considerable number of animals from different horizons in Patagonia, and while * It has been pointtfl out that this name was used by Haeckel (Denerelle IMorphologie, vol. iii. p. clvii) to include certain genera of extinct Marsupials, and the alternative name Einbrithopoda has boon suggosteil (Nature, vol. Ixxiii. (1900) p. 221). INTRODUCTION. XV many of these (e. g. Archwohyrax) do not seem to differ in any important ])articulars from some of the smaller Typotheria, others of the more primitive forms belonging to Ameghino’s family, the Acadodidae, may perhaps approach the ancestral forms from whicli the Ilyracoidea originated. Althongh Ar sin oi they him is certainly the most^ extraordinary of the Ungulates found in these beds, nevertheless the remains of the primitive members of the Proboscidea are perhaps of greater scientific interest, because they help to fill, at least to a large extent, one of the most obvious gaps in our knowledge of the extinct Mammalia. Previous to their discovery the earliest Proboscideans known were from the Lower Miocene (Burdigalien) of Europe and Northern Africa, and although many earlier deposits rich in mammalian remains were known in various parts of the world, in none of them was any trace of Proboscidea found, so that their appearance in Europe at the beginning of the INliocene period must be the result of their immigration from other regions. The probability that Africa would be found to be the original home of these animals was pointed out by several writers, notably by Osborn, Stehlin, and Tullberg. The first of these * suggested that probably not only the Proboscidea but also the “ Hyracoidea, certain Edentates, the Antelopes, the Giraffes, the Hippopotami, the most specialised Ruminants, and among the Rodents the Anomalures, Dormice, and Jerboas, among Monkeys the Baboons,” and, as his map suggests, the Sirenia also, originated in this region. Osborn also put forward the theory that a succession of migrations from Africa to Europe occurred, notably at the end of the Eocene, at the beginning of the IMiocene, and again in the earliest Pliocene. It was in the early Miocene migration that the Proboscidea passed out of Africa for the first time so far as known. Stehlin f, who also emphasized the importance of Africa as a probable centre of mammalian evolution, expressed much the same views. Tullberg J likewise regarded Africa as a centre of mammalian radiation, and pointed to Ilystrix (or the uhole of the Hystricognathi), the Simise (Anthropoidea), and the Proboscidea as having probably migrated thence in the early Miocene. It is therefore very satisfactory * “ Correlation between Tertiary Mammal Horizons of Europe and America,” Arm. N. Y. Acad. Sci. vol. xiii. (1900) pp. 1-72. t “Ueber die Geschichte des Suiden-Gebisses, Pt. II.,” Abbaudl. d. Schweiz. Palaeont. Gesellsdi. vol. xxviL (1900) p. 477 et seq. 7 “Ueber das System der Nagetiere,” Nov. Act. E. Soc. Sci. Upsala, [3] vol. xviii. (1899) p. 483. Also for the general question of mammalian distribution, see Lydekker, Geographical History of Mammals (^1890).^ ” ' ■ c2 XVI INTKODUCTJOX. that tltc earliest traces of land-inaniinals from the Eocene of Africa include remains of primitive rrohoscidea, as well as early forms of llyracoidea, Sirenia, and perhaps some of the other groups. 'file eai-liest-known rroboscidean is Mvpj'ifherium, which occurs first in the Qasr-el- Sag’.ia beds (Middle Eocene) and persisted till the Upper Eocene, its remains having been found in the Elnvio-marine series. This animal was about the size of a Tapir, which it must have greatly resembled in general appearance. The skull (see fig. 40, j). 100) presents no very striking peculiarities, the chief points of interest being that (1) the nasals are short and the nasal opening is not quite at the end of the snout ; (2) the bones of the back of the skull tend to become swollen by the presence of air-cells; (8) the maxillae send forward on the palate [)rocesses which help to support the enlargetl second incisors. The mandible is short and stout, its ascending ramus being inclined a little forwards ; the symphysis is spont-like and the upper surface is continuous with that of the sloping lotver incisors. 'I he teeth are of greater interest. The dental formula is i. o, c. pm. vi. so that of the complete ])rimitive Entherian dentition only one lorver incisor, the lower canine, and the first upper and lower preniolars are wanting. Of the upper incisors, the second pair are greatly enlarged, forming trihedral dosvinvardly directed tusks ; the others as well as the canine are quite small. The three premolars are all simpler than the molars, but the fourth approaches them most nearlv. I'he prcmolars replace milk-teeth in vertical succession in the ordinary wary. The molars consist essentially of four low' blunt tubercles, arranged so as to form two transverse ridges ; the last upper molar has a very small posterior lobe in addition to the main ridges. In the low’er jaw only the first and second pairs of incisors remain : of these the median ones arc small, the second enlarged and tnsk-like ; both slope strongly forwards and their upper surface is continuous with that of the spout-like symphysis. The canines and first premolar are entirely lost, and, as in the upper jaw', all the remaining premolars are simpler than the molars, although the last approaches them in complexity. The molars are on the w'hole like those of the upper jaw, but on the first and second there is a very small posterior ridge which in the third becomes a large talon. In the vertebral column the most striking point is that the axis retains the 2)eg-like form of its odontoid such as occurs in generalised Ungulates, e. (j. the Pig, and at the same time the centra of tlie cervicals are not shortened to any great extent, so that no doubt the animal could reach the ground with its mouth in the ordinary way. INTliODUCTIOX. X\ 11 The limbs are unfortimately not well known. The humerus ditfers considerably from that of the later Proboscidca, but some of tlie smaller species of Paloeomadodon (see text-fig. 50) from the Ujiper Eocene seem to supjily intermediate forms: probably the difference arises from the fact that Mceritlteriimi was a more or less amphibious type, while the later Elephants became fitted for progression on firm ground. The femur approximates very nearly to the form found in the later Proboscideans. As already mentioned, Maeritherium was probably an amphibious, shore, or swam]) living animal, and it was no doubt owing to the continuation of the conditions favourable to its mode of life that it persisted into the Upper Eocene period. In the meantime, however, either from this or some closely allied type, there had arisen another animal more adapted to terrestrial life and showing a great advance in the direction of the typical Proboscidca : to this creature the name Palceomastodon has been given. The intermediate links between it and Mceritherium or some allied form are not yet definitely known, unless some of the smaller species referred to Palceomastodon, under the names P, minor Kndi P. jjarvus, or the animal called M. trigonodon, oxe such. Certainly in many respects the limb-bones, particularly the humerus (see text-fig. 56, p. 164), referred to P. parvus, are both in size and structure intermediate between those of Mceritherium lyonsi and Pal oeo mastodon headnelli. The largest species of Palceomastodon {P. headnelli) must have been about the size of a half-grown Indian Elephant : in its general appearance it was Elephant-like, but differed in having a longer neck and the symphysial portion of the mandible prolonged beyond the skull (see text-fig. 48, p. 131) and covered only with the fleshy snout. Probably it could reach the ground with its lower incisors, and the end of the snout may already have been prehensile. In the skull the chief peculiarities are : (1) the external nares are shifted backwards, so that they are only just in front of the orbit, and, in consequence, the nasal bones are shortened and relatively very small ; (2) the back of the skull is greatly enlarged by the development of spongy bone in the occipital region. The occipital surface above the prominent condyles slopes a little forwards and has a deep median fossa for the attachment of muscles. The upper dentition is much more reduced than in Mceritherium, and now assumes more definitely Proboscidean characters. The only remaining incisors are the large tusk- like second pair, which are directed downwards and have a band of enamel on their outer side. Sections of these tusks examined microscopically show no traces of the peculiar “ engine-turning” so characteristic of the dentine of the tusks of the later forms. Either this structure was only acquired when the tusks became greatly enlarged or the will IXTKODUCTIOX. condition of'llic sjicciinens cx;uniiicd is not favourable to its preservation. The canine and tiie tirst jin'inolars arc lost; the other prcinolars are evidently undergoing reduction, but at tlic same time the last has become bilophodont. The molars are all triloiihodont, each transverse crest consisting of at least two distinct tubercles; there is also a tendency to the addition of another posterior ridge from the cingulum. One notable point about tlie molar series is the sudden enlargement of the second and third true molars, compared with the teeth in front. This is accompanied by the considerable development of cellular tissue in the posterior part of the maxilla and the neighboniing bones, and appears to be the first indication of the great increase in the size of tlie posterior molars found in later types. This increase in the size of the maxilla, which is probably correlated with the general tendency of the bones of the posterior part of the skull to develop diploe, seems almost as if it were a pre])aration for the subsequent changes in the teeth, but, on the other hand, it is possible that the increase in their size may be in part a consequence of possessing more room in which to develojx As already noted, the mandible is greatly elongated in the symphysial region, and its- ascending ramus slopes backwards, both modifications tending to increase the distance the animal could reach with its lower incisors. Of these there is a single pair (the second) projecting forwards from the symphysis: the canines and first and second prcinolars are lost; the other premolars and molars are generally similar to those of the upper jaw. In the vertebral column the axis still has a peg-like odontoid process and a comparatively long centrum, though the centra of the posterior cervicals arc much shortened. The limb-bones, so far as known, are closely similar, except in size, to those of Flephas. In general appearance J^alaomasfodon must have resembled a small rather long- necked Elejihant, the most notable different'e fieing that the trunk, instead of lieing freely flexible, was supported by, and formed the upper covering of, the elongated mandibular symphysis ; its extremity, however, may iiave been free and to some degree prehensile. The further history of this group can only be briefly summarised here (see Phil. Trans. 19G b, 1903, p. 99). The next form, Tetr((heIodon angnstidens from the European Lower Miocene, has the sym})hysis still more elongated and the narial opening shifted further back. At the same time the molars, or at h ast the posterior ones, are greatly increased in size and possess more transverse ridges. There are three milk-molars in both jaws, and the posterior two are succeeded in the normal way by premolars ; INTRODUCTION. XIX but, in consequence of the increased size of tlie posterior molars, the premolars, and eventually even the anterior molar, are shed as the posterior molars come into position from behind. This animal attained the size of a moderately large Indian Elephant, and except for the inflexibility of the mandible-supported trunk must have been very similar in appearance. In the later Miocene the mandibular symphysis shortened, leaving the trunk mobile and unsupported, as we now know it ; at the same time traces of its original elongated condition are retained in the occurrence ot deciduous lower incisors in some species of Mastodon and in the peculiar sharp process of the symphysis in the Elephants. In the teeth there is a gradual increase in the number and height of the ridges composing the molars, together with the great increase in the size of the individual teeth. The milk-teeth are never replaced by premolars, but are early dis[)laced by the advance of the molars into position from before backwards; the culmination of this line of evolution is met in the latest Elephants, in which in old age the only cheek-teeth in position are the very large third upper and lower molars. The above is, of course, only a general summary of the succession of forms which lead up to the modern Elephants, and no doubt there haA^e been many checks and side-branches leading only to extinction in the course of the vast period that has elapsed since Moeritheriuni existed. The position of Banjtherium in relation to the other Ungulates is quite uncertain. It cannot be related to Arsinoitherium, since not only are the teeth Avidely different in type, but the anterior part of the dentition, in the mandible at least, has undergone great modification, the anterior lower premolars, canines, and posterior incisors having been lost and the anterior incisors modified to form large procumbent tusks. In this respect it approaches the primitiA'e Proboscidea, but the fore limb so far as knoAvn differs widely from the Proboscidean type : this is especially noticeable in the distal articulation of the radius, Avhich rather resembles that seen in Uintatheriiiin than that found in the Elephants, and seems to show that the carpus differed considerably from that of the latter group. Another possibility must be referred to, namely, that some kind of relationship with the Pyrotheriidue of Patagonia may exist ; in both the molars are bilophodout, the anterior lower incisors tusk-like and procumbent and separated by a long diastema from the premolars, the other incisors, the canine, and anterior incisorfe being lost ; in the carpus also the scaphoid seems to have been large in both groups. The probability of such a relationship Avill be discussed beloAv. The Artiodactyla, AA’hich are represented in the Upper Eocene by members of the Anthracotheriidm and Suidac, may possibly be regarded as a foreign element in this XX INTRODUCTTOX. fn.uiia, nltlioi]'reat]y in size and nnnil)er of transverse ridges. b)i', Chalmers INIitcliell lias lately sliown ('frans. Zool. 8oc. vol. xvii. 1905, pp. 4G4-7) that the Sirenia and l’rol)()scidea rescmihle (uie another in the arrangement of tlie intestinal tract and that in neither group is there any trace of the Ungulate specialisation : it is also significant that he states that Ihjrax likewise approaches the Sirenia in this respect. In a former ]):i[)er (I’hil. 'J'rans. vol. 19C b(1903) p. IIG) it was stated that the possession of a non-deciduate zonary jdacenta was common to the two groups in question, but it has been pointed out by Messrs. Assheton and Stevens (Quart. Journ. Micr. Sci. vol. xlix. 1905, ]). 1) that this is an error, and that, as a matter of fact, in the Proboscidea the |)lacenta is deciduate. At the same time, these writers show that in both groups the placenta, in addition to the short villi, also possesses a number of larger and longer \ irii, which deeply penetrate the maternal tissue and seem to be torn off at parturition. Although these points of similarity, taken separately, may be of no groat value, together they supply a very strong argument in favour of the close relationship of the two orders. All the Carnivora at present known from the Upper Eocene of the Fayilm belong to one family, the Ilyienodontida?, of the primitive group, the Creodonta. They are remarkable from the fact that in the four genera represented, viz. Sinopa, Apterodon, I’fcrodon, and lipcenodou, the molar teeth show four stages in the development of the cutting-blade and in the reduction of the talon and the postero-internal cusp. It seems highly probable that these animals entered Africa from the north, where Creodonts are found in the earlier Eocene deposits ; but at the same time the fact that the Zeuglodont Protoccdus from near the bottom of the Lower Mokattam beds, has a dentition which is practically that of a Creodont, clearly indicates its origin from members of that group, which may therefore have inhabited this region at a still earlier period. Since, however, Protoccdus is already fully adajhed for marine life, this is by no means certain, for it may have crossed from the northern side of the Nummulitic sea. Another argument for the existence of earlier Creodonts in the Egyptian region is that, since there is considerable probability that Africa was connected by a land-bridge with South America in late Cretaceous and possibly even at the beginning of the Tertiary period, their presence in Africa would account for the existence of the Sparassodonta in the Tertiaries of Patagonia. The Zeuglodonts of the Fayum, taken together with a species, Protoccdus atavus, recently described by Prof. E. Fraas (29) from the limestones of the Mokattam Hills, form a series showing a complete transition, so far at least as the dentition is concerned, TNTJiODUCTIOX. XXI 11 from the Crcodonts to the true Zeiiglodonts. In the earliest type, Protocetus, the skull is already practically that of a Zeug-lodoiit, the rostral jiortion being, in fact, even more elongated than in some of the later forms ; at the same time, however, the opening of tlie nares is situated nearer to the end of the snout. The teeth are most remarkable; the incisors are not known, but the rest of the dentition is practically that of a typical Creodont, none of the teeth having assumed the peculiar serrated form characteristic of the later Zeuglodons. The canine is large, with a single though grooved root ; the first premolar is much smaller, the second large and two-rooted, the third and fourth have posterior cus^^s and are supported by three roots; the molars, which are small, are also three-rooted. In Prozeuglodon (p. 243) from the later Birket-el-Qurun series the skull is likewise essentially Zeuglodont, tliough the external nares have shifted a little further back. The canine is much larger than the teeth before and behind it, and although the third and fourth premolars and the molars have serrated crowns, as in the later Zeuglodons, they, or at least the premolars, retain their inner buttress supported by a third root, so that in tooth-structure this genus is exactly intermediate between Protocetus and Zeucjlodon. Fraas (29) has lately described still another annectant form, Eocetiis, from about the same horizon as Prozeuglodon, which attained a very large size ; the skull approaches that of Zeiiglodon in the position of the nares, but the teeth are Creodont-like and possess inner (third) roots. Kemains of Zeuglodon itself seem to have been found in the same deposits as these intermediate types, but that genus continued to exist in the Qasr-el-Sagha beds above after they had disappeared. The Birds are represented in these beds by one or two fragments only, but those of considerable interest, because they show that most likely a true Batite [Eremopezus) existed in this district in the Upper Eocene period. This is of importance, because it indicates that possibly some at least of the main subdivisions of the Eatitm may have had a common ancestry in the Ethiopian region. If so, this would account for the likeness between the ^.pyornithes and Struthiones referred to by Burckhardt, and also suggests the possibility of the relationship between these groups and the South- American Ivheas. It is, of course, just possible that this genus is merely another instance of the results of retrogressive modification leading to loss of flight and increase in size in some group of Carinate Birds, such as has occurred in the case of the Gastornithes and Stereornitbes ; in any case, much more material is required before any final conclusion can be reached as to the precise position of this genus. The Reptiles are represented by members of the orders Crocodilia, Chelonia, and d2 WIV INTliODUCTIOX. ()])lii(lia. 'i'lie Crocodilia, rc'inains of wliicli occur in both the Middle and Upper Mocene beds, are of no special interest, the most important point being the occurrence of the genus Tomisioma, a further ])roof of the former wider range of this genus, which at the i)resent day is r('])resented by a single species found in the rivers of Borneo, Sumatra, and Malacca. One of the species now described is interesting, as being in seveial features intermediate between Gliarialis and Tomistoma, in this respect a])in-oaching the genera Thoracosnnrus and Gavialosuchus, the latter of which, however, is regarded by Mr. Lydekker as identical with Tomistoma. Among the Chelonia the Athecate group are represented only by a species of Psc])]iOj)iiorns, the humerus of which represents the extreme degree of modification for jx'lagic life. This form occurs in tlie marine Middle Eocene beds, where it is accompanied by remains of another Sea-Turtle, a member of the genus Tlmlnssocheltjs. The terrestrial Cryptodira, remains of which are confined to the Fluvio-niarine (Upper Eocene) beds, are represented by several very large species of Testndo, Avhich approach in size the giant Tortoises of Madagascar, the Mascarene and Galapagos Islands. In the presence of a nuchal shield and double gulars, they approach most nearly the 'bortoises of Aldabra and Madagascar, and may, in fact, be the direct ancestors of those species, as well, possibly, as of some of the extinct Indian forms. The occurrence of numbers of the shells of such strictly terrestrial forms as these, mingled with tree-trunks and bones of mammals, makes it clear that we owe these richly fossiliferous deposits to floods sweeping down a great river draining a land-area lying immediately to the south or south-west (see Beadnell, ‘ lieport on the Ea}u m.p. GO). The rieurodira are represented in both the Middle and Upper Eocene beds : two genera are at present known, one [Slercogenys) especially remarkable on account of the modification of the mandible and ])alate for crushing the food. In the mandible the greatly enlarged symphysis is broad and flat; and in correlation with this a secondary hard palate is formed by the meeting of the maxilhe and palatines in the middle line beneath the nasal passage, so that the internal narcs open far back, behind the lev('l of the crushing-surface of the jaws. The other genus of Bleurodirans is Podocnemis, remains of which are found both in the Middle and Upper Eocene beds of this region. The same genus also occurs in the Lower Eocene of England and India, but at the present day is confined to Madagascai- and South America. This ])eculiar distribution suggests that although those Chclonians may in the tirst instance have reached the Ethio])ian continent from the north, probably it was thence that they INTRODUCTION. XXV spread to their present habitats, the genus becoming extinct elsewhere, though it persisted in Egypt till the Miocene. The Ophidia are re])rescnted by two genera only : one Gifiantoplus, a Python of very largo size, the other Pteros])henus, of which one species, P. sclmeinfurtJd , is found in the Eayuin, while another, P. schucherti^ occurs in the Eocene of Alabama ; in both localities remains of Zeuglodonts are abundant in the same beds, a circumstance which, coupled with the peculiar structure of the vertebric, shows that these Snakes were aquatic and probably marine. Nevertheless, it does not seem likely that they would cross oceans of great width, and tlieir presence in Egypt and in Alabama seems to be an argument in favour of the presence of a shore-line across what is now the Atlantic Ocean, probably lying somewhat to the south. The presence of primitive Sirenians in Egypt (Potherium) and the West Indies {Proradomus) is explicable on the same grounds. No Amphibia have yet been found, and the Fishes are of no great interest, being all either Elasmobranchs or Siluroids : among the former occur several types of Sawfish, while the latter are chiefly remarkable for their great similarity to forms now living in the Birket-el-Qurun and the Nile. From the above summary of the contents of this Catalogue, it will be seen that a very considerable number of early Tertiary Vertebrates, especially Mammals, are already knowm from Egypt, and that practically all of them have been discovered since the beginning of 1900, so that, although Professor Osborn writing in that year could say of Africa with truth, “ It is the dark continent of Palaeontology, for it has practically no fossil mammal history,” this reproach is at least in a fair way to be removed. At present, of course, the species known must be a mere fraction of the faunas inhabiting the Ethiopian region during the Middle and Upper Eocene periods, but the proportion of peculiar types included in them is great enough to show how fully justified the writers above referred to were in their assumption that the Ethiopian continent in early Tertiary (and perhaps pre-Tertiary) times Avas a very important centre of mammalian evolution. The question of the relations of this Ethiopian region to the rest of the world is one of very great interest. The probability of a series of temporary land-connections between it and the Pahearctic continent has already been referred to above and has been fully discussed by Osborn, Stehlin, Tullberg, &c. ; in all cases so far as known these connections occurred during the Tertiary period. Furthermore, the probability of a former land-connection with South iVmerica has been argued with much force by X.W 1 TNTJiODUCriON. ii nuinlx'r ()1‘ aulliors, including, among otliers, Amcghiiio * * * §, Blanford f , Boulenger l.ydc'kker 1^, Ncumayr||, Ortmann Scott** * * §§, Sucssff, and von IheriiigJJ. These Avriters, basing their argnincnts on many diverse kinds of evidence, all seem to arrive at the general conclusion that a land-connection did exist between Africa and South America throughout at least most of the Secondary period and may have persisted into the Lower Tertiary. Concerning the precise position of this land-connection, and whether it may have existed at more than one point, there is some diversity of oj)inion, but these differences do not seem to be of any great importance compared with the general agreement that there must have been such a connection. Speaking generally, it appears that (1) probably in Jurassic times Africa and South America formed a continuous land-mass ; (2) in the C’rctaccous period the sea encroached southwards over this land, forming what is now the South Atlantic. How far this depression had advanced southwards at the end of the Secondary period is not clear, but it appears certain that the final separation of the two continents did not take place till Eocene times, and that there may have been a chain of islands between the northern part of Africa and Brazil u hich persisted even till the Miocene On the assumption that this series of events did happen, there is little difficulty in accounting for most of the peculiarities in the distribution of the various groups. Thus, to mention only a few instances, the presence in both continents of the Hystrico- morphine Bodents, of Chelonians of the family Belomedusidic, and of the Fishes of the family Cichlidm is at once accounted for. So also is the presence in the Santa Cruz * La Argentina al travtts cle las Ldtiinas Epocas Geologicas (Buenos Aires, 1897). Also “Liuea InlogencHica cle los Proboscicleos,” Anales Mus. Nac. Buenos Aires, vol. viii. (1902) p. 19 ; and “ Les Edentes fossiles de France et d’Allemngne,” he. cit. col. xiii. (190o) p. 175. t Presidential Address to the Geological Society, 1890. t Presidential Address to the Zoological Section, Brit. Assoc. (South Africa, 1905). § A Geographical History of Maiiiuials (189G), p. 127. jj Erdgeschichle (1890), p. 370. “Geographical Lislribiition of Freshwater Decapods and its Bearing on Ancient Geography,” Proc. Ainer. Phil. Soc. vol. xli. (1902) p. 267. ** Deports of the Princeton University Expeditious to Patagonia (1890-1899) — Palaeontology, vol. v. pt. ii. (1905). ft Das Antlitz der Erde, vol. ii. (1888). Jl; “ On the Ancient Delations between New Zealand and South America,” Trans. New Zealand Instit. vol. XXV. (1891) p. 431. §§ For evidence of tlie probable existence of shallow water across this rc^gion, perhaps as late as the Miocene, see Gregoiy, Qeait. Journ. Gtol. Soc. vol. li. (1895) p. 300. [NTIIODUCTIOX. xxvu beds of Xecrolestes, apparently a close ally of the Cape Golden Moles, and of the Sparassodoiita, which, after all, seem to be Creodonts and not Marsupials. Further- more, light is also thrown on the numerous points of similarity between Struthioncs and the llhem, especially when it is remembered that a large Ratite bird, Ereinoj^tezvs, existed in the Eocene of Africa. As to the Ungulates, it seems likely that the separation of the two areas took place when the main divisions were only just beginning to be differentiated, and that groups like the Pyrotheria and the Arcluuo- hyracidac are not ancestral to the Proboscidea and llyracoidea of the Old 'World, but more probably represent terms of partly parallel scries which had a common ancestry on the common land-surface before the separation of the two regions took place. If this were so, we should expect to meet with a general resemblance between the various groups rather than a close similarity of structure, and this, in fact, is what we find. In the case of the occurrence of the primitive Sirenian Prorastomus in the West Indies, and of the Water-Snake Pterosplienus in the Eocene beds of Alabama, it seems likely that these animals passed either along the southern coast of the Eocene Atlantic or across the bridge of shallow water between the chain of islands above referred to as probably lying between West Africa and Brazil. The fact that the mammalian fauna of Madagascar is a comparatively poor one and entirely lacking in many of the groups that must have inhabited the Ethiopian mainland, is considered by Tullberg to be accounted for by supposing that the eastern part of Africa with Madagascar was separated from the main South-west African continent by an arm of the sea, and that it was not till after the isolation of Madagascar (probably in the late Oligocene) that the two portions of Africa became united. At this time East Africa was probably united to South-western Asia by continuous land, along which the Proboscidea reached India, and perhaps thence penetrated to North America. In both these regions, as well as in Europe, the group seems to have undergone the further series of modifications which gave rise to the modern type of Proboscideans. Another consideration which adds to the importance of Africa as a centre of mam- malian evolution has been pointed out by Stromer (42), namely, that part of it at least has probably never been submerged since the Palaeozoic period, and formed a portion of a vast Permo-Triassic land-area inhabited by a great variety of mammal-like Theriodont reptiles from which the Mammalia may have actually arisen. This being the case, it is not only the Tertiary, but also the Secondary, deposits of this region that may be expected to yield most important data for the history of the Mammalia. INTRODUCTION-. xxviii From tlic foregoing summary it will be seen that Africa appears to offer a most ])romising field for the Verfebrate Palccontologist, and it is greatly to be desired that travellers, whether geologists or not, should observe and record the position of any beds that contain bones, even if mere fragments only are found. In conclusion, I wish to express my sincere thanks to Captain H. G. Lyons, Director- General of the Egy])tian Survey, for kindly allowing me to describe the Vertebrate remains preserved in the Geological Museum, Cairo, in conjunction with those in the British Museum, and by so doing to increase very greatly the value of the present volume. 1 am also greatly indebted to him for valuable advice and assistance in arranging my own collecting-expeditions. Best thanks are also due to Mr. W. E. de Winton, whose generosity made my visits to Egypt in 190-3 and 1901 possible. I am indebted to Dr. W. F. Ilume, of the Geological Survey of Egypt, for much help when working in the Museum at Cairo, and to Mr. II. -I. L. Beadnell, late of the same service, for the privilege of accompanying him on his visit to the Fayiim in 1900, and for much help subsequently in working my own collecting-expeditions. Thanks are also due to Mr. C. Davies Sherborn, wdio kindly volunteered to make the Index to this volume ; to the Council of the Zoological Society and the Editors of the Geological Magazine for the loan of illustrations ; and, finally, to Mr. F. O. Barlow for his help in collecting in the early part of 1903, for the subsequent suceessful l)reparation of the specimens obtained, and also for the preparation of excellent models of the restored skulls and mandibles of McerWierium and PaJeeomastodon. CITABLES W. ANDREWS. 1. 1 S T OF PUBLICATIONS REFERIUNG TO THE TERTIARY VERTEBRATES OE EGYPT. 1. Abel, 0. Die Sirenen der niediterranen Tertiarbilduiigen Oesterreichs. Abhandl. k.-k, geol. Reichsanstalt, vol. xix. pt. 2 (1904). 2. . Die ph}dogenetisclie Entwicklung des Cetaceengebisses und die systeinatiscbe Stelluiig der Pbyseterideii. Verhandl. deutseh. zool. Gesellscb. 1905, j). 84. 3. Ameghiho, F. Liiiea Filogenetica de los Proboscideos. Anales Mus. Nac. Buenos Aires, vol. viii. (1902) p. 19. 4. Andrews, C. W. Fossil Mammalia from Egypt. Pt. I. Geol. Mag. [4] vol. vi, (1899) p. 481. Pt. IT. „ vol. vii. (1900) ji. 401. 5- • On a new Species of Cheloiiian {Podoaiemis ceguptlaca) from the Lower Miocene ot Egypt. Geol. Mag. [4] vol. vii. (1900) p. 1. 6. '. Preliminary Note on some Recently Discovered E.xtinct Vertebrates from Egypt. Pt. I. Geol. Mag, [4] vol. viii. (1901) p. 400. Pt. II. „ . „ p. 430. Pt. III. „ vol. ix. (1902) p. 291. 7" • Note on a Pliocene Vertebrate Fauna from the VVadi Natron, Egypt. Geol. Mag. [4] vol. ix. (1902) p. 433, pi. xxi. 8. -. Notes on an Expedition to the Fayum, Egy})t, witb De.scri[>tions of some new Mammals. Geol. Mag. [4] vol. x. (1903) p. 337. 9. . On some Pleurodiran Cbelonians from the Eocene of the Fayum, Egypt. Ann. it Mag. Nat. Hist. [7] vol. xi. (1903) p. 115, pis. vii., viii. 10. . On the Evolution of the Proboscidea. Phil. Trans, vol. 19()B (1903) p. 99. I I. . On the Pelvis and Hind-limb of Midleronns hetdlei, M.-Edv\. it Grand. ; with a Not<“ on the Occurrence of a Ratite Bird in the Ui)per Eocene Beds of the Fayum. I’roc. Zool. Soc. 1904, vol. i. p. 1()3. >2. . Further Notes on the Mammals of the Eocene ot Egypt. Pt. I. Geol. Mag. [,5J vol. i, (1904) p. 109. Pt. 11. „ „ p. 157, pi. vi. Pt.III. „ „ p. 211. • 3. . The Barypoda, a new Order of Ungulate IMammals, Geol. Mag. [5] vol. i. (1904) p. 481. e \xx 7JST OF PUBLICATIONS. 14. AxDitEWS, C. W. Noto on ihe (lio'aniic Lunrl-Tortoise {Testiulo arnmon^ from the Upper K()C(oio of Egy])t. Geol. Ma^. [5] vol. i. (1904) p. 527, pi. xvii. 15. . Nofos oil some new Oroeodilia from the Miocene of Egypt. Geol. Mag. [5] vol. ii. (1905) p. 481. 16. . Note oil the Sixaiies of Puhromastodon.. Geol. Mag. [5] vol. li. (1905) p. 5G2. 17. Andrews, C. W., & Beadnei.e, H. J. L. A Preliminary Note on some new Mammals from the Upper Eocene of Egypt. Survey Dept., Cairo, 1902. 18. , . A Preliminary Notice of a Land-Tortoise from the Upper Eocene of the Fayum, Egypt. Survey Dept., Cairo, 1903. 19. Be .VDNEi.E, 11. d. L. The Fayum Depression ; a Preliminary Notice of a District of Egypt containing a new Palaeogene Fauna. Geol. Mag. [4] vol. viii. (1901) p. 540. 19 rt. . Decouvertes Geologiijues Recentes dans la Vallee du Nil et le Desert Libyen. VIII. Congr. Geol. Internat. 1900. Paris, 1901. 20. . A Preliminary Note on Ars'ui(ykherit/m zitfeli, Beadn. Survey Dept., Cairo, 1902. 21. . The Topography and Geology of the Fayum Province of Egypt. Pp. 1-101 ; jilates i-xxiv. (photographs, maps, and sections). Survey Dept., Cairo, 1905. 22. Be.vnckenhorn, M. Neues zur Geologie nnd Paliiontologie Aegyptens. Pt. II. Das Palaeogen. Zeitschr. deutsch. geol. Gesellsch. vol. Hi. (1900) p. 403. Pt. III. Das Miociin. Oj). cit. vol. liii. (1901) p. 52. Pt. IV. Die Pliociin- und Quartarzeitalter in Aegypten ausschliesslich des Rothen Meergehietes. Tom. cit. p. 307. 23. . Neue geologisch-stratigraphische Beobachtungen in Aegypten. Sitzungsber. d. math.- pbys. Classe k.-bay. Akad. Wissensch. Miinchen, vol. xxxii. (1902) j). 353. 24. . Die Geschichte des Nilstromes in der Terliar- und Quartar[)eriotle, etc. Zeitschr. Gesellsch. f. Erdkunde, vol. xxxvii. (1902) p. G94. 25. Dames, AV. Ueber eine tertiilre AVirbelthierfauna von der vvestliclien Insel des Birket-el- Curun im Fayum (Aegypten). Sitzung.sher. d. k. preuss. Akad. Wissensch. Berlin, 1883, pt. 1, p. 129, pi. Hi. 26. . Amhh/pristls Cheops, nov. gen., nov. sp., aus dem Eociin Aegy}>tens. Sitzungsber. Gesellsch. naturf. Freunde, Berlin, 1888, p. lOG. 27. . Ueber Zeuglodonten aus Aegyjiten und die Bezieliungen der Arclucoceten zu den iibrigen Cetaceen. Ikilajont. Abliandl. n. s. vol. i. (1894) p. 189, |)ls. xxx.-xxxvi. 28. Filhol, H. Note sur la decouverte d’un nouveau Mammifcre marlu (Manatus coitlombi) en Afrique dans les carriere.s de Mokattam pres du Caire. Bull. Soc. IMiilomatli. Paris, [7j vol. ii. (1878) p. 124. 29. Fkaas, E. Neue Zeuglodonten aus dem unteren Mitteh'ociin vom Alokattam bei Cairo. Palaiont. Abliandl. n. s. vol. vl. (1904) j>. 199, jils. x.-xii. 30. Owen, R. On Fossil Evidences of a Sirenian Mammal (TJothcrinm (cpi/ptiacitm, Owen) from the Nummulitic Eocene of the Mokattam Cliffs, near Cairo. Quart. Journ. Geol. Soc. vol. xxxi. (1875) p. 100, pi. Hi. 31. PRIEM, F. Note sur Projmstis, Dames, du Tertlaire inferieur d’Egypte. Bull. Soc. geol. France, [3] vol. xxv. (1897) p. 228. Sur les Poissons de I’Eoccne du Mont Mokattam ( Egvpte). Bull. Soc. geol. France, [.3] vol. xxv. (1897) p. 212. 32. LIST OF FUJ3LICATIONS. XXXI 33. PuiKM, F. Sur dos Poissons I'ossiles eocenes d’E^ypte, etc. Bull. Soc. geol. F/ance, [ii] vol. x.wii. (18t'9) p. 211. 34. Rkinach, a. von. ScliildkriJtenresto aus dein iigyptischen Tertiilr. Abliandl. d. t^enckenl). naturl’. Gesellscb. vol. xxix. (19U3) p. 1, pis. i.-xvii. 35. ScnwEiNKiiRTii, (1. lleise in das De[)ressiongebiet iin Umkreise des Fajuin iin Januar ISSti. Zeitsclir. Gesellscli. f. Erdlvundcj Berlin, vol. xxi. (1880) p. 9G. 36. Smith, G. Elliot. The Brain of the Arclneoceti. Proc. Roy. Soc. vol. Ixxi. (1903) p. 322. 37. Sthomeu, E. Wirbeltierreste aus dem inittleren Pliociin des Natrontales und einige subfossile und recente Silugetierreste aus Aegypten. Zeitsclir. deutsch. geol. Gesellscb. vol. liv. (1902) p. 108 (Brietliche Mitthl.). 38. . Bericht iiber eine von den Privatdozenten Dr. Max Blanckenhorn und Dr. Ernst Stroiner von Reichenbach ausgeftihrte Reise nach Aegypten. Sitzungsber. d. inath.-phys. Classe k.-bay. Akad. Wissensch. Miinchen, vol. xxxii. (1902) p. 341. 39. . Haifischezahne aus dem unteren Mokattain bei Wasta in Aegypten. Neues Jahrbuch, 1903, vol. i. p. 29. 40. . Einiges iiber Ban und Stellung der Zeuglodonten. Zeitschr. deutsch. geol. Gesellscb. vol. Iv. (1903) p. 30 (Protokolle). 41. — . Zeiiglodon-Vidiie aus dem obereu Mitteleociin des Fajum. Beitr. Pal. u. Geol. Oesterreich- Ungarns u. d. Orients, vol. xv. (1903) p. 05, pis. viii.-xi. 42. . Ueber Afrika als Entstehungzentrum fiir Siiugethiere. Zeitschr. deutsch. geol. Gesellscb. vol. Iv. (1903) p. 01 (Protokolle). 43. . Nematognathi aus dem Fajum und dem Natronthale in Aegypten. Neues Jahrbuch, 1904, vol. i. p. 1. 44. . Die Fischreste des inittleren und oberen Eociius von Aegypten. Beitr. Pal. u. Geol. Oester.-Ungarns u. d. Orients, vol. xviii. (1905) p. 37, pis. v. & vi., and p. 163, pis. xv ct xvi. 45. . Fossile Wirbeltier-Reste aus dem Uadi Natrun und Uadi Faregh in Aegypten Abhandl. Senckenb. naturf. Gesellscb. vol. xxix. (1905) p. 99. 46. Studer, Th. Ueber fossile Knochen vom Wadi Natrun, Unteregypten. Mitteil. naturf. Ges. Bern, 1898, p. 72 (1899). 47. Woodward, A. S. On the Dentition of a Gigantic E.xtinct Species of Myliohates from the Lower Tertiary of Egypt. Proc. Zool. Soc. 1893, p. 558. On the Fossil Fish-spines named Caelorliynclius, Agassiz. Ann. & Mag. Nat. Hist. [6] vol. ii. (1888) p. 223. 48. SYSTEMATIC INDEX. ♦♦♦>♦ — Page Class MAMMALIA l Order UNGULATA 1 Suborder BARYPODA 1 rainily AESiNOiTnEiaiD.i 2 Arsinoitherium 2 zitteli 64: aiidrewsi 80 SuI)order HYRACOIBEA 83 I'aniily 8aghatiieeiid.e 84 Sagliatherium 84 antiquum 85 minus 89 magnum 89 majus 91 Megaloliyrax 92 eocsenus 92 — miuor 96 Suborder PROBOSCIDEA 99 4'amily Mcerithekiid,® 99 Moeritherium 99 lyonsi 120 gracile 127 trigonodoii 128 sp 129 Family Pae.eomastouoxtid-E 130 Falteomastodon 130 beadnelli 150 wintoni 156 parvus 162 minor 168 Phiomia 169 serridens 170 lacertin scdis. Family BAnyTiiERTin.E 170 Barvtherium 172 grave 17G Page Sahorder ARTIOBACTYLA 178 Family ANTUEACOTnERiiD.E 178 Ancodon 178 gorringei 179 parvus 189 sp 191 Hhagatberium 191 aegyptiacum 192 Family Scid.e 193 Geniohyus 193 mirus 193 fajumensis 195 major 196 Order SIRBNIA 197 Family IIaliooiiid.e 197 Eosiren 197 libyca 198 Order CAENIVOEA 218 Family IlY.ENOuoNTiDyE 218 llyaenodon 218 Pterodon 219 al'ricanus 220 Apterodon 225 macrogiiathus 226 Sinopa 232 etliiopica 233 Order CETACEA Suborder ARCIEEOCETI Family Zeuglouoxtii>.e Zeuglodon osiris isis Prozeuglodou atrox ./■ 234 234 234 236 236 240 243 X\1V SYSTEM ATIC IXDKX. Page Glass AVES 258 Order EAd'lT.E 258 Eremopezus 258 pnf»fr>nns . . . . . . 058 Class REPTILIA 261 Order CEOCODIFIA 261 Suborder EUSUC III A 201 Family Cu(jCouilid.e 2(;i Crocodilus 201 articeps 261 me"arliimis 204 sp 1206 6’oniistonia 207 jrn.vlnloirlc's; .... .... 207 africanum 270 keruneuse 274 Order CHELOXIA 275 Suborder ATlIECzE 275 Family Spii.^hgid.e 275 Psepbopborus 275 eocoenus 275 | Suborder TIlECOPIIOItA 277 I Division A. CiiYPToniiiA . . . . Family Testuuixid.e Testudo ammoii beadnelli isis . . . . 277 . . . . 277 .... 277 .... 278 285 286 Family Ciieloxip.e .... 287 Thalassocbelvs 287 libyca . . . . 287 Division B. Pleuiiodir.v .... ‘'89 Family Pelojiedusid.e 289 Podocnemis 282 antiqua 289 fajumensis . 291 Page Family Pelomedusio.e (roni.). Stereogenys 295 cromeri 295 • libyca S02 Order SQUAMATA 306 Suborder OPlflDIA 306 Family Eoiu.e 306 Grigantopliis 307 garstini 307 Family PAmEOPiuD-E 309 Pterosphenus 309 scbweinfurthi 310 Class PISCES 313 Subclass TELEOSTOMI 313 Order ACTIXOPTEEYGIl 313 Suborder OSTARIOPIIYSI 313 Family Silttiud.e 313 Fajumia ... 313 scliweiiifui'tbi 313 Socuopsea 315 grandis 315 Subclass ELASMOBEANClIIl .... 317 Order SELACHII 317 Family Peistid.e 317 Pristis 317 fajumensis 317 Proprist is 318 sch\\eiiifurtlii 318 Eopristis 318 reiiiachi 319 Family JMymoii.vTiD.E 319 Aetobatis 319 Family L.iviunid.!'; 319 Carcharodoii 319 LIST OF ILLUSTRATIONS IN THE TEXT. Eig. Page 1. A rsinoitlierium zitteli : skull, seen from behind 3 2. 55 skull, oblique view of anterior portion, showing the relation of the nasal and maxilla to the narial opening 8 3. 55 skull, diagrammatic section through snout at the level of the third premolar 11 4. 55 skull, side view of orbital region with the zygomatic arch removed 13 5. 59 95 cast of cranial cavity 16 G. 59 andrewsi : seiiii-diagrainmatic fioure o£ the in)per and lower teeth of the left side 18 7. 55 zitteli : : semi-diagrammatic figure of the upper milk-molars .... 21 3. 59 99 atlas vertebra 25 y. 55 55 axis vertebra 26 10. 5> 59 cervical vertebrfe 28 11. 59 99 anterior thoracic vertebra 29 12. 99 99 middle thoracic vertebra 29 13. 59 99 posterior thoracic A crtebra 30 14. 99 99 (?) sacral vertebra 31 15. 99 99 left scapula 33 10. 55 99 left humerus 35 17. 95 99 left radius 36 18. 99 95 left ulna 38 19. 99 99 left forearm and manus 40 20. 99 99 left sca[)hoid 41 21. 99 99 right lunar 42 22. 99 99 left cuneiform and pisiform 44 23. 55 99 left magnum 45 24. 99 99 left unciform 46 25. 95 99 fifth left metacarpal 47 26. (?) 55 55 pelvis from back 48 27. 55 99 pelvis from side 48 28. 99 99 right femur 50 29. 99 59 right patella 51 30. 95 59 right tibia 52 9 XXWl LIST OF TTvLUSTKATIONS IN THE TEXT. I'-ig. :?i. :V2. :i;5. M. I>5. o7. :58. :u). 40. 41. 42. 43. 44. 4,-'). 4(;. 47. 48. 40. 50. 51. 52. 53. 54. 55. 5(). 57. 58. 50. GO. 61. G2. G3. G4. G5. GG. G7. (18. GO. 70. 71. 72. Page Arsinoklicrliun z'dlell : l(4’t (ihiila 53 ,, „ l(4't calcaiUMun and astragalus 55 „ ,, l(4'r, navic'ular 57 „ ,, right cuhoid 58 ,, ,, nudatarsals 50 ,, ,, la'stored .skeleton GO ,, „ ])elvis and hind limbs (il ,, aiidreirs}. : left hunierns 81 eocfvniis : posterior j)ortion of skull 05 Manitheriinn Ii/onsi restored skull and inandil)le 100 ,, ,, cast of the cranial cavity lOG Maslodon atnerlcanns : cast of the cranial cavity 107 MtrrifJieriinii li/oiisi : ]iart of right ramus of an immature mandihh' Ill Manrdherinni : anterior dorsal vertebra 114 ,, middle dorsal vertebra 114 ,, lumbar vertebra 115 ,, sacrum IIG l\da’oinastodon. : semi-diagrammatic figure of the skull and mandible EU A. Pahcomastodon ; B. Kd'phas : the base of the skull and part of the palate . . . 134 A. Fahiomadodon beadnelli ; B. F. u'intoni ; C. F. paiTiis ; D. F. niiiior: the second and third lower molars 143 Falceomastodon headnelli : left calcaneum 148 Falceomastodon-. right astragalus 140 F ahvomastodon uinfoni : mandible 157 „ ,, mandible 150 ,, parvus: right ramus of mandible 1G.3 (?) ,, „ right humerus 1G4 (?) „ ,, right ulna IGG (?) ,, ,, right tibia 1G7 (?) j, ,, left astragalus 1G7 A7icodo7i (jo7'7‘'wgei : left os innominatum 185 „ „ right a.stragalus 188 „ parvus: portion of right ramus of mandible 100 Gc7dolt7/us 7uaJor : left lower premolars lOG Kosire7i Uhpva : portion of roof of skull 200 ,, „ cast of the cranial cavity 202 (?)Eot}ie7'iu7/i (rggpfiacu77i : skull 205 ,, „ mandilde 211 A. IIaUt}te7’iin7i ; B. Jdos'ire7i ; C. Fotlie/‘iu7)i (after Abel ) ; D. A/a!ritlteriu/7t : right ossa innominata 214 (?)Pferodo7iafrica7ms: anterior ])art of skull 222 (?) ,, „ loft humet us 223 (?) ,, ,, right femur 224 Apfe/’udo/i 7)tarrog7iathus : left ramus of mandible 22G IJST OF JLLUSTKATIONS IN THE TEXT. XXXVll Fig. Fage 7.'5. Apterodon macrngnathus : portion of right ramus of maiulihle 228 74. (?) „ „ loft humerus 22i) 75. (?) „ „ right tihia 280 7(). (?) ,, „ right astragalus 2;H 77. ZeiKjlodoa osiris : left ramus of mamlihle 288 78. ,, ists\ right ramus of mandible and premolar tooth 241 70. (?) ,, „ vertebra 24)5 80. Prozeuglodon atrox'. restored figures of skull and mandible 244 81. „ „ posterior surface of skull 245 82. „ „ palatal view of left [)remaxilla and maxilla, with pm. 8 and pm. 4 . 250 88. ,, „ anterior cervical vertehrai 258 84. Kremopezus eocanns : distal end of left tibio-tarsus 259 85. Crocodilus megarhinus : anterior portion of skull 265 86. Tomistoma africanum •. anterior portion of snout 271 87. Psephopliorus eocamus : left humerus 276 88. Testvdo amnion : restored shell 279 89. „ „ plastron 280 90. „ „ pelvis 288 91. „ headnelli: plastron 285 92. Podocnemis antigiia : carapace and plastron 290 98. „ fajumensis : anterior portion of plastron 292 94. (?) „ „ carapace and plastron 298 f>5. Stereogengs cromeri : palatal view of skull 296 9(i. „ „ carapace and plastron 299 97. ,, lihijca : carapace and plastron 808 98. Pristis fajumensis : rostrum 317 itt ~ to S ' ^ y f li A DESCRIPTIVE CATALOGUE OF THE TERTIARY VERTEBRATA OF THE EAYUM, EGYPT. Class MAMMALIA. Order UNGULATA. Suborder BARYPOD A. [C. W. Andrews^ Geol. Mag. [5] vol. i. (1904), p. 481.] Full eutherian dentition without diastemata. Molars tending to become hypsodont ; premolars differing widely from molars. Anterior palatine foramen very large and single. Alisphenoid canal present; no condylar foramen hitherto observed. Brain- cavity relatively much larger than in the Amblypoda. No entepicondylar canal in the humerus ; no third trochanter in the femur. Both feet probably pentadactyl. Fore foot much like that of the Proboscidea ; the metacarpals alternating to the same extent as in Elephas, and the scaphoid closely similar to that of the latter genus. Ulna entering into the carpal joint much more extensively than the radius; the cuneiform consequently large and sometimes overlapping the magnum, and the scaphoid relatively small. Flind foot differing widely from that of the Proboscidea, and approaching that of the Amblypoda. Astragalus and calcaneum both bearing large fibular facets ; the low broad astragalus articulating distall y with the cuboid and navicular, the former having only a small surface of contact with the calcaneum. A small tibiale probably present. From the shape of the calcaneum it seems probable that the heel sometimes rested on the ground. B 9 TEliTIAliY VEETEBRATA OF THE EAYtTM. family ARSINOITHEllIID.^:. Comprising only the genus Arsinoitherium, and not yet precisely definable. Genus ARSINOITHERIUM, Beadnell. [Prelim. Note on Arsinoitherium zitteli, Beadn. : Survey Dept., Cairo, 1902.] Occipital surface of skull strongly inclined forwards ; a pair of small frontal horns over the orbits, and a pair of enormous nasal horns arising from a common base constituted by the nasals and frontals. In the adult, a prenasal bar of bone uniting the anterior border of the nasals with the premaxillae. Orbit open posteriorly. Palate strongly arched from side to side. Molars bilophodont. Neck very short. Humerus and femur considerably longer than the radius and tibia respectively. So far as known, this genus is represented by two species only in the Upper Eocene of Egypt. Nearly all parts of the skeleton have been discovered. Skull (Pis. I., II., III. ; text-figs. 1-4). — The skulls in the collections belong to individuals of various ages, ranging from young animals in which the last molar is still uncut and most of the sutures remain open (PI. III. fig. 2) to fully adult individuals with the last molar much worn and almost all the sutures obliterated (Pis. I., II.). An intermediate condition is shown in PI. III. fig. I, where the last molar is just coming into wear, and some of the sutures {e. g. that between the exoccipital and squamosal) are still open, while the horns are rounded and the character of the bone shows that growth was actively proceeding at their summit. An adult skull in the British Museum (Pis. I., II.) suffices for the greater part of the general description, and this specimen is important because it was found in actual association with its mandible. The general appearance of the skull is most remarkable. Seen from behind (text- fig. 1) the most notable characters are: — (1) The large size and great prominence of the occipital condyles ; (2) the extreme inclination forwards of the occi])ital surface ; (3) the great development of the lambdoidal crest, the lower ends of which form strong prominences in the adult animal. In a front view (PI. II. fig. I a) the appearance is very curious, the two great horns and the sharp wedge-shaped extremity of the snout giving the whole a triradiate form. Beneath the base of the horns are the two very large narial apertures, divided in the adult by a vertical prcnasal bar of bone. An upper view of the skull (PI. III. fig. 2) shows the large widely- separated and prominent condyles, the forwardly-inclined occipital surface, and in ARSINOITIIEEIUM. 3 front of this the nearly flat parietal region, passing anteriorly into the rounded common base of the great horns. The zygomatic arch does not project very strongly, and Skull of Arsinoitherium zitteli, seen from behind. hoc., basioccipital ; cond., condyles ; exo., exoccipital ; f.h., frontal born ; f.m., foramen magnum ; in.n., internal nares ; n.Ji., nasal born ; prominence of squamosal ; pterygoids ; g.c., lambdoidal crest ; sot’., supraoccipital. ^ nat. size. the widest part of the posterior portion of the skull is situated just above and behind the auditory opening. In a palatal view (PI. II. fig. I) the peculiar wedge-shaped 4 TEirriAJiY VEllTBBliATv^. OF TILE FAYtTM. tbriii of the skull is well shown, other notable points being the highly arched palate and the large median anterior palatine foramen. 'The exoccipitals (exo.) seem to form the whole of the great occipital condyles, though the sutures between them and the basioccipital are obscure. The condyles {text-lig. 1, cond.) themselves are somewhat pedunculate and project entirely beyond any other portion of the skull. Their inner faces are flattened, wdth a deep depression near their base. The articular surface is much less convex from side to side than fnuu above downwards, in which direction the curvature of the surface is nearly a semicircle. In firct, the articulation may almost be described as a slightly oblique section of a cylinder, and must have allow'ed great freedom of movement to the head in an up-and-down direction. There is no condylar foramen, or at least none has yet been observed. The foramen magnum (text-fig. 1, f.m.) is large and oval in outline. Its concave upper border is formed entirely by the exoccipitals, which meet in a median suture, thus excluding the supraoccipital entirely from the opening (PL III. fig. 2) ; while its ventral border, which is nearly straight and somewhat posterior to the upper border, is probably formed mainly by the basioccipital. The suture between the exoccipitals and the supraoccipital runs outwards and somewdiat upwards from the middle line (PI. III. fig. 2), and crosses the low'er end of the massive lambdoidal crest, of which the thickened and prominent ventral end is therefore formed by the exoccipital. Laterally the exoccipitals are applied by a broad surface to the posterior face of the post-tympanic process (PI. I., PI. II. fig. I, PL III. figs. I, 2A,pty.) of the squamosal, the suture between the two being nearly vertical. Between this squamosal process of the exoccipital and the condyle, below the level of which it projects considerably, there is a blunt prominence, W'hich seems to represent the paroccipital process (PL I., PL III. fig. The hasioccipital [hoc.), wdiich, as already mentioned, forms the nearly straight ventral border of the foramen magnum (text-fig. I, f.m.), is broad and flat posteriorly, but its outer boundaries are not clear. Antero-laterally it seems to be notched on either side by the posterior angles of a pair of large fossae, which open into the cranial cavity, are separated by the narrow anterior portion of the bone, and must in life have lodged the tympanic bones. The anterior portion just mentioned deepens considerably from before backwards, so that near its junction with the basisphenoid the vertical diameter is much greater than the transverse extent. In this anterior region the ventral surface bears a median keel, while a transverse ridge marks its junction with the hasisphenoid (PL II. fig. I, hsp.), the ventral surface of which is likewise keeled in the middle line. The axis of this bone is not quite in the same straight line as that of the basioccipital, but turns slightly upwards in front, its anterior portion being embraced by the upper edges of the pterygoids posteriorly and of the palatines anteriorly. The vomer has not been observed in any specimen. ARSINOlTIIElllUM. 5 The siqrraoccipital {soc.), as already mentioned, is excluded from the foramen magnum. It forms the whole of the upper part of the sloping occipital surface, which is bounded above by the thickened, rugose, and very prominent lambdoidal crest [s.c.]. This seems to be situated along the junction of the supraocci])ital and the parietals, though it is impossible to determine ])recisely which is the line of union, since even in the youngest specimens the suture is closed. In the middle line there is a prominent ridge for the attachment of the ligamentum nuclice., and on either side of this the surface is greatly roughened, like the surface of the lambdoidal crest. The parietals [pa.) are not only fused with the supraoccipital, but also with one another in the youngest specimens available for examination. In the immature skull figured on PL III. fig. 2 there is, in the middle line of the skull-roof, a small foramen, which opens into the sinus occupying this part of the cranial wall and is probably a remnant of the sagittal suture. This opening is absent in other specimens, and therefore cannot be regarded as of importance. The parietals form the anterior portion of the lambdoidal crest, in front of which they constitute the skull-roof, which is nearly fiat from side to side, and slightly concave from before backwards. Laterally they turn downwards almost at right angles, and help to form the side-walls of the skull, their lower edges meeting the squamosals in a nearly straight suture, which runs downwards and forwards (PI. III. figs. 1, 2 a). The upper edge of this lateral region of the parietals is sharply defined by the strongly- marked ridge, which forms the upper limit of the temporal fossa and is continued forwards on the frontals as far as the orbits. In the adult the fronto-parietal suture is closed, but in the young (PI. III. fig. 2) it can be seen that the parietals extend forwards in the middle line between the small frontal horns. Immediately behind these the fronto-parietal suture turns forwards to the supratemporal ridge, after crossing which it turns downwards and somewhat backwards, running down to join the parieto-squamosal suture. The squamosal [sq.) is a large and complicated bone which takes a considerable share in the formation of the side-wall of the cranium. Its sutures with the parietal and exoccipital have already been referred to. It cannot be determined whether or not it had any contact with the supraoccipital, but probably its upper posterior angle, which helps to form the large lateral occipital prominence, united with that bone at least for a short distance. Beneath this prominence the surface of the bone is roughened and raised into a ridge, which in the adult skull forms a strong, backwardly-directed, hook-like process (text-fig. 1, pr.) for the attachment of muscle, situated above and rather behind the opening of the external auditory meatus (Pis. I., II. fig. 1, e.a.m). Ventrally the bone is produced downwards into a broad post-tympanic flange {])ty.), which terminates below in a blunt point and is supported posteriorly by the downward process of the exoccipital TEKTJAJiY VEKTEBKATA OF THE FAYCM. (; mentioned in the account of that hone. The post-tympanic process [ptu.) curves forwards and forms tlie posterior wall of the large external auditory meatus {e.a.m.). 'I'he anterior wall of this opening is formed by an extremely long and broad postglenoid process which curves backwards so as nearly to meet the lower end of the ])ost-tympanic. The outline of the external auditory meatus is oval, the long axis being nearly vertical ; the meatus narrows somewhat towards its inner end, where it opens into the large fossa occurring on either side of the basis cranii, and no doubt lodging in life the petrosal and tympanic, the latter of which may liave extended into the passage between the post-tympanic and ])ostglenoid processes just described. In one skull (M. 8463) a portion of the inner surface of the petrosal is preserved, but in all other cases both that bone and the tympanic are wanting, leaving the large vacuity just referred to. The glenoid surface (Tl. 11. tig. gl.) is much wider from side to side than from before backwards; it is slightly concave in the former direction, and rather more so in the latter. Internally it is bounded by a deep groove, which separates it from the upper end of the ])terygoid plate, and outwardly it extends upon the base of the zygomatic process, 'fhis latter is stout and is laterally compressed anteriorly, where it terminates in a sharp point. Ventrally it unites in suture with the jugal, which extends back beneath it to the level of the anterior border of the glenoid surface. The sharp u[)per edge of the zygomatic process is continued backwards and upwards as a ridge forming the posterior and outer boundary of the temporal fossa. The upper surface of the squamosal between this ridge and the parieto-squamosal suture forms a sort of concave door to the posterior portion of the temporal fossa ; the anterior boundary of this surface is the sharp trout edge of the glenoid articulation fPl. II. fijir. 1 and PI. III. tig. 2). The frontals (/)■.) not only form the lower part of the upper surface and the hinder portion of the sides of the base of the great anterior horns, but each of them also bears a small horn, which is situated near their junction with the parietals and on the outer edge of the skull-roof. These small horns are hollow and their cavity is continuous with the extensive sinus occupying the great anterior horns and the roof of the skull generally. This sinus will be described below. The parieto-frontal suture has already been referred to ; that between the frontals themselves persists for some time, and both it and the fronto-nasal suture are shown on PI. III. figs. 2, 2 A. It will be seen that the fionto-nasal suture first runs nearly vertically downwards, then downwards and forwards, and finally directly downwards, meeting the fronto-maxillary suture nearly at right angles. This latter suture runs directly backwards until just outside the border of the orbit, where the two bones are separated by the small square lachrymal ; within the orbit they again unite, the suture between them running downwards to a large orbito-nasal foramen (oii.f., see text-fig. 4, p. 13). The supratemporal ridge is continued on the frontals AKSINOITIIEKIUM. / from the parictiils and sharply defines the upper border of the temporal fossa. It ends some distance in front of tlie small horns, and its termination may be taken as marking the posterior limit of the upper border of the orbit, there being no definite postorbital process. The antero-superior portion of the orbital border is formed by the frontal; it is broadly rounded, and at one point near the middle it is crossed by a broad shallow depression, which runs upwards and forwards on to the side of the base of the born, where it divides into three or four divergent branches, forming deep channels in the bone (PI. I,, h.v.). These channels evidently lodged blood-vessels which served for the conveyance of blood to or from the covering of the horn, and judging from the marked way in which both these vessels and those on the anterior face of the horns impress the bone, it seems probable that the covering was hard and of much the same nature as that clothing the horn-cores of the cavicorn ruminants. The lachrymal {1.) is a small bone occupying the anterior angle of the orbit, wedged in between the frontal above, and the maxilla and jugal below. It bears a vertically-elongated prominence (see PL I., 1.) which forms the actual edge of the orbit and is connected below with a strong crest borne on the front of the maxillary process of the jugal. There seems to be no trace of any lachrymal foramen. The nasals {na.) are the most remarkable bones of the skull, and they are enormously enlarged, forming almost the whole of the great anterior horns. The sutures between these bones and the frontals have already been referred to ; they are open only in the young (PI. III. figs. 2, 2 a); in the adult or even three-parts-grown animal they are completely obliterated (PL I. and PL III. figs. 1, 1 a), and the same is the case with the suture between the nasals themselves. On the side of the face the ventral border of these bones unites first with the upper edge of the maxilla, and in front of this with the premaxilla, the suture with which is continued forwards just into the nasal cavity. Here a downgrowth of the lower surface of the portion of the nasals forming the roof of the nasal cavity unites with a corresponding upgrowth of the maxilla which overlaps it (text-fig. 2). The two form a sort of column on either side of the posterior face of the nasal cavity, and these columns help to support and form a base for the horns. Furthermore, owing to their presence the nasal passage is greatly contracted and forms a vertical cleft between them. The roof of the nasal cavity is nearly fiat and in the adult its edges are thin, sharp, and somewhat everted (PL I., PL II. fig. 1a): in the young, on the other hand, this edge is wanting (PL III. figs. 2 A, 2 b), so that the nasal roof passes by a gentle curve into the outer face of the horn. In the young also the anterior ends of the nasals are free and not connected by a bar of bone with the premaxillae. This bar, which is formed only at a comparatively advanced age, appears to result from the ossification of the anterior edge of a cartilaginous nasal septum, the presence of which is indicated by the peculiar groove (PL III. figs. 1a, 2 b, ms.y. ; see also text-fig. 2, mes.y) 8 TEliTIAliT VEUTEERATA OF THE FAYOM. situated hetweoii the ii|)])er edges of the facial processes of the premaxillae: this will he described Jiiore fully in the account of the latter bones. The anterior face of the ])renasal bar is flattened and towards its lower end deeply pitted by what seem to be muscle-impressions: possibly the animal possessed a pointed mobile upper lip, something like that of lildnoceros hicornis, and the muscles inserted in these impressions were concerned in its movements. The general form and relations of the prenasal bar are well shown in PI. I. and PI. II. fig. I a; also in text-fig. 2. Text-fig. 2. Skull of Arsinoiilierium zitteli: oblique view of anterior portion showing the relation of the nasal and maxilla in the narial opening. a. 0. f., antorbital foramen; f. 1, f. 3, incisors ; ji’m., jugal; lachrymal; nics., prenasal bar; wies.f/., mesethmoid groove ; «i.r., maxilla ; na., nasals ; nar., nares ; pm. 2, pm. .3, premolars ; pmx., premaxillcC. ] nat. size. I'he horns themselves are borne on a common base, formed by the frontals posteriorly, but for the rest by the nasals alone. The mid-dorsal line of the basal portion is marked by a shallow groove, but in the adult the median suture is completely obliterated. A section of the basal region taken at right angles to its dorsal surface would give an arc of about three quarters of a circle, though somewhat inflated at the sides. From this base the paired horns arise and project forwards, upwards, and somewhat outwards. In adult, probably male, animals they AT^SINOITIIEEIUM. 9 ave somewhat triaiigolav in section : the sharp anterior angle is continued down- wards to the border of the nasal opening (PI. I. and PL IT. tig. 1 a). 'J'lie inner face is nearly fiat, the posterior is also flattened, while the outer side is rounded. In what may be regarded as an adult female skull the horns are much smaller, more erect, and very irregularly ossified at their tips, which are rounded anteriorly, but terminate posteriorly in an irregular mass of bone. This skull was figured by Mr. Beadnell in his original paper (pis. iii.-v.). The specimen in question is fully adult, for the last molar is well worn, all the sutures are closed, and the prenasal bar fully ossified. In the young the horns are rounded at the summit, where the bone is of a peculiarly fibrous or spongy texture, showing that growth Avas actively proceeding at this point. The central portion of the horns is occupied by an enormous sinus, the walls being relatively thin, about '5 cm. to 1 cm. in thickness in the adult, and much less in the young. The sinus occupies the bodies of the nasals and frontals and in the latter extends into the small supraorbital horns. Furthermore, it extends back into the parietal and in the old animal even into the base of the lateral prominences of the lambdoidal crest. In the cranial region the sinus is more or less completely divided into a right and left half by a median septum occupying the position of the suture between the parietals. Flere the lower table of bone forming the actual wall of the brain- case is very thin, while the upper table is greatly thickened. In the frontal and nasal regions the separation into tw’o halves is not complete, but there is both in the mid-dorsal and mid-ventral line a greatly thickened ridge projecting into the cavity of the sinus ; the ventral ridge is the stronger and forms a laterally compressed bar of bone. These main longitudinal thickenings are connected transversely by less prominent, more or less regularly arranged thickenings of the walls, and these again are occasionally united by irregular ridges. In the paired portion of the horns there are only transverse ridges running round the cavity, with some irregular secondary ridges joining them at a few points. The great anterior horns thus consist of comparatively thin bony walls, which are strengthened by a complex system of buttresses, and are further braced against thrusts in the direction of their long axis by the columns resulting from the union, of the nasals and maxillm above noticed, and, in the adult, by the prenasal bar. The surface of the horns is marked by a series of shalloAV grooves running mon* or less in the direction of their long axis and frequently anastomosing. On the antero-lateral faces of the horns, a little above the nasal opening, there are impressions of blood-vessels (see PI. I., h.v.') similar to those described on the frontals. The ‘pfemaxillm {pinx.) are relatively small bones. The alveolar bolder of each, as usual, bears three incisor alveoli. Of these the first pair is considerably the largest ; they are rounded with a raised border and are separated in the middle line by an interval of about 2*5 cm., in which the edge of the bone is rounded and c 10 TEKTIAliY VEIiTEBRATA OF THE FAYCiM. rougliciicd. 'riic other alveoli are smaller, compressed from before backwards, and crowded together ; they arc separated by a very small space from the socket of i. 1 ill front and by none at all from that of the canine behind. The palatine portion of the jiremaxilloc is small : the premaxillo-maxillary suture runs backwards from immediately behind the alveolus of the last incisor, and the bones form little more of the palate than the high arched roof of the unpaired anterior palatine foramen, the ])osterior or ventral edge of which is formed by the anterior border of the palatine jilatcs of the maxillae. The facial portions of the premaxilhn form the very narrow Avedge-shaped extremity of the snout, the actual angle of wdiich is somewhat truncated and roughened. The suture wuth the maxilla (Pis. I., II., III.) runs upwards and backwards to a point midway between the nasal opening and the orbit ; and in front of this the bone unites Avith the nasal, the suture Avith Avhich runs just into the narial opening. Within the latter the premaxilla again meets the maxilla, forming a suture with the upAvard prolongation of that bone, which together Avith a doAvngrowth of the nasal forms a support for the large horns in the manner above described (see the description of the nasals and text-fig. 2). The posterior part of the border of the nasal opening formed by the premaxilla is rounded, but in front of this the bone is bent iiiAvards and doAviiAvards and terminates internally in an irregular roughened edge, the posterior angle of Avhich forms a blunt tuberosity. This inturned edge is separated from the corresponding portion of the bone of the opposite side by a deep groove (text-fig. 2, mes.g.), which in life probably lodged the loAV’er edge of a vertical cartilaginous nasal septum. In the young this remains unossified, but in the fully adult animal its anterior region ossifies and forms the prenasal bar of bone joining the nasals Avith the premaxillse, as above described (see Pis. I., II. fig. 1 a; also text-fig. 2). In consequence of the great size and the hypsodonty of the teeth, the maxilla (mx.) is very large. Its facial suture Avith the premaxilla has already been described, and it Avill be noticed that it is completely excluded from the margin of the nasal opening by the meeting of the premaxilla and the nasal. Within the nasal opening, hoAvev'er, it is produced upAvards into a process Avhich unites with a doAvngroAvth of the nasal in the manner already mentioned. Pehind its union Avith the premaxilla the upper border of the bone meets the frontal, and its suture Avith that bone terminates just behind the antorhitul foramen {a.of.), at Avhich point the small lachrymal is interposed, and helps to form the outer side of the bar of bone Avhich closes the antorbital foramen externally. This foramen is very large and opens by a Avide passage into the orbit. The maxilla is excluded from the actual margin of the orbit by the junction of the lachrymal Avith the upper end of the jugal, Avhich sends up a long process forming the Avhole ventral border of the orbit, and uniting anteriorly Avith the maxilla. The zygomatic process of the maxilla is very short, extending very little AliSINOITIIEEIUM. 11 behind the posterior border of the alveolus of the last molar. The facial surface of the bone slopes inwards, especially in its anterior portion (see PI. II. fig. 1 a). The suture between the maxilla and premaxilla crosses the alveolar border immediately behind the last incisor. On the palate it runs backwards for a short distance, behind which the anterior edge of the maxilla becomes free and forms the lateral and hinder borders of the large median anterior palatine vacuity (PI. II. fig. 1). The anterior portion of the palatal surface formed by the maxilla is very highly arched, so much so, in fact, that the sides of the palate are nearly parallel with the facial surface of the bone (see text-fig. 3), the Text-fig. 3. Skull of Arsinoitherium zitteli : diagrammatic section through snout at the level of the third premolar. c., centre about which the teeth move in growth ; mes.g., mesethmoid groove ; mx., maxilla ; mx.pmx.s., maxillo-premaxillary suture ; ynn. 3, third premolar ; pmx., premaxilla. | nat. size. distance between them being practically the width of the alveolar surface. This peculiarity seems to be mainly due to the deepening of the alveolar region of the bone in order to carry the high-crowned and long-growing cheek-teeth. The diagram given in text-fig. 3 is a vertical section of the snout taken at the level of the third premolar, showing that the teeth and the deepened portion of the maxilla form a continuous curve which is almost a part of a circle with the centre at the point c. The growth of the teeth along this curve accounts, in a great c2 12 TliliTIARY VERTEBRATA OF THE FAYtlxM. measure at least, for tlio mucli greater height of the outer side of the crown than of tlie inner side. 'I’lie same diagram also shows in section the junction of the maxillae with the ])r('maxill;e {ntx.pmx.s.), and the probably mesethmoid groove {mes.g.) which lies between the upper ends of the premaxilloe and was no doubt occupied in life by the lower edge of a vertical cartilaginous nasal septum. Another possible explanation of the deeply concave palate is, that Arsinoitli erium may have possessed a tongue of peculiar form, probably extensible and ])rehensile ; for it is difficult to understand how an animal of such great size could grasp sufficient food with so extremely narrow an incisor region if it had not some additional means of prehension in the form of a mobile up])er lip or tongue. Further back the palatal surface of the maxilhe becomes more flattened, and opposite the second molar these bones unite with the palatines in a broad transverse suture ; behind this point they only appear on the palate as a narrow strip on either side, llehind the last alveolus the maxilla is produced backwards into a short pointed ])rocess which forms the outer wall of a foramen (PI. II. fig. I, m.p.f.)^ the rest of which is a deep notch in the edge of the palatine. Above this foramen the hinder border of the maxilla forms the outer edge of a groove {p-P-g.), running up towards the anterior opening of the alisphenoid canal (text-fig. 4, al.c.). This groove and foramen, which seem to be homologous with the posterior palatine foramen of the human skull, also occur in Ilgrax (Procavia) and possibly other Ungulates, and no doubt transmitted branches of the jjalatine nerve and blood-vessels. The foramina to which the name posterior palatine is applied in most mammals lie on the palate at or near the junction of the anterior end of the palatines with the maxillae ; and these openings are also present in Arsinoitherium, though very small. Probably both pairs of openings simply mark the points at which the palatine vessels and nerves ])assed between the maxillas and the palatines, when these bones were still separate in the young ; and the presence or absence of the anterior or posterior of the foramina mentioned depends on whether the palatine nerves and vessels passed out iu one or more groups on either side. In Arsinoitherini)i the posterior openings are large, and those near the anterior end of the palatines small, owing probably to some structural peculiarity which rendered necessary a larger nerve- and blood-sup])ly for the ])osterior region of the palate. In some animals there is a series of small loramina on either side, the anterior one usually being much the largest. In front of the posterior edge above mentioned the maxilla widens into a large mass, which in the adult lodges the roots of the posterior molars, and in the young, in which it is relatively still larger, contains the develoj)ing germs of the same teeth. This alveolar mass to a considerable extent forms a floor to tlie orbit. Although the maxilla is excluded from the actual border of the orbit by the union of the lachrymal and jugal, it nevertheless forms a large part of its anterior wall iu the neighbourliood of the posterior opening of the antorbital canal, where it unites in suture with the ARSINOITJIEKIUM. 13 frontal, and behind this appears to form the ventral edge of an elongated orbito-nasal foramen (text-fig. 4., on.f.), opening from the orbit into the nasal passage, llehind this again the maxilla joins the orbital portion of the palatine in a suture running backwards some distance till it disappears in the depression marking the inner side of tlic swollen alveolar mass of the bone. Text-fig. 4. Skull of Arsinoitheriicm zitteli : side view of orbital region with the zygomatic arch removed. a4r., alispheuoid canal; a.o./., antorhital foramen; 6.r., impressions of blood-vessels ; external auditory meatus ; ? vascular foramen ; fJi., frontal horn ; f.l.a., foi-amen lacerum anterius ; fr., frontal ; ju., jugal; 1., lachrymal; m. 2, m. 3, molars; mx., maxilla; on.f., orbito-nasal foramen; pa., parietal ; injl., postglenoid process; pi., palatine; p.p./., posterior palatine foramen ; p.p.^r., posterior palatine groove ; pt., pterygoid ; pty., post-tympanic process ; sq., squamosal ; st.r., supratemporal ridge ; t.f., temporal fossa ; ii., optic foramen. \ nat. size. The jugal (PI. I., PI. III. figs. 1, 2 k,ju.) articulates in front with the malar region of the maxilla by a long process which runs up as far as the anterior angle of the orbit, where it meets the lachrymal and completely excludes the maxilla from the margin of the orbit, as already mentioned in the description of that bone. Immediately below and in front of the orbit there is a very prominent, rough, curved ridge (marked ju. in text-fig. 4) which projects considerably from the side of the face and must have served 14 TEETIARY VEETEBRATA OF THE FATtM. lor Il)(' atlachiTicnt of ])0\vcrful muscles. Beneath the orbit the jugal bar is narrower (Voni above downwards, but it is consideraLly thickened ventrally and bears several sti’ong ridges. Posteriorly it turns upwards and widens out to some extent, meeting tlie zygomatic process of the squamosal in a long and nearly straight horizontal suture. 'J'he posterior angle of the jugal extends well back behind the anterior border of the glenoid surface, of wliich it may even help to form a part at the outer border. I'lie liolatines form the greater part of the hinder region of the palate, as well as of the side-walls of the nasal canal and of the mesopterygoid fossa. The union of their palatine plates with the maxilla is nearly transverse in front, and in or near the siiture there is a pair of small posterior palatine foramina (PI. II. tig. 1, ]>}>■/.), to which reference has been made above. The anterior end of the palatines is op])osite the posterior column of m. 2 in the adult skull : behind this the maxillo- j)alatine suture runs backwards and slightly outwards. The posterior border of the palate is opposite the hinder end of m. 3 : it is greatly thickened and on either side of the median suture there are two rougliened ridges directed 'forwards and outwards. Behind the palate the ventral edges of the vertical plates of the bones are greatly thickened and deeply notched externally, the notch forming the greater part of the ])osterior foramen (PI. II. fig. 1, m.p.f.) which has already been described in speaking of the maxilla. A little behind this the palatines join the pterygoids (PI. II. fig. I,yj/.), which form only a comparatively small portion of the descending plates which bound the mesopterygoid fossa. From the ventral edge of the plate the palato- pterygoid suture runs first forwards and upwards, then directly upwaards to the hasis cj'anii, which is overlapped and embraced by the upper edges of both palatines and pterygoids. The palatines also form the side-walls of the posterior portion of the nasal canal, and appear on the inner wall of the orbits above the alveolar mass of the maxilla, with which they unite in suture behind, and from which they are separated by the orbito-nasal foramen in front. The relations of these bones to one another and to the surrounding structures can be best understood by examining a skull of Uendrohyrax {Procavia) dorsalis, in which the sutures all remain open. The upper edge of the orbital plate of the palatine must have united with the orbito- sphenoid, but the suture cannot be made out ; indeed all the boundaries of the orbitospheuoid and alisphenoid are obscure, partly because these bones are very thin and greatly cracked. The pterygoids {pt.) form only the posterior part of the deep vertical plates wdiich enclose the meso{)terygoid fossa. The suture between them and the palatines in front has already been referred to. Their ventral border is thickened and convex : posteriorly they end in a slightly ])rominent angle (see PI. I.), above which the posterior border of the bone is very thin. The upper edge of the bone unites with the basisphenoid and runs high np on the side of that bone into the opening- lying between it and the glenoid surface of the squamosal, an opening doubtless ARSINOITIIERIUM. 15 partly filled in life by the tympanic, which is wanting in all the skulls hitherto examined. The upper posterior edge of the pterygoid within this opening forms the inner border of a deep groove lying between it and the squamosal and probably representing the foramen lacerum medium (the foramen lacerum anterius of some German authors). As already remarked, the boundaries of the alisphenoid and orhitosplienoid are by no means clear. The alisphenoid appears to send down a long narrow plate to the outer face of the vertical palatine plates, with which its lower end is intimately fused, forming a prominence which is seen in PI. I. at the end of the reference-line running from the letters p/. Further up, this alisphenoid plate is perforated by the short wide alisphenoid canal (text-fig. 4, al.c.), the anterior opening of which lies within the anterior edge of the plate, which is continued upwards and forwards as a prominent downwardly directed crest of bone, forming the outer side of a deep groove, at the bottom of which there are several foramina in addition to the alisphenoid canal. The most important of these is a large somewhat vertically elongated opening, the foramen laeerum anterius {foramen sphenoidale of some authors). Above and slightly internal to the foramen lacerum anterius, and separated from it by a narrow bar of bone, is the smaller and more rounded optic foramen (Pis. I., II. ; also text-fig. 4, ii.) opening into a groove, of which the upper edge is constituted by a continuation of the crest formed by the border of the alisphenoid plate, the lower edge being much less prominent and probably approximately marking the lower border of the orbitosphenoid, in which the foramen itself is no doubt situated. Above and in front of the optic foramen there is a very small aperture, probably for a blood-vessel. Several more or less nearly complete casts of the cranial cavity have been made, that upon which the accompanying figures (text-fig. 5) are based being taken from the skull figured on Pis. I. and II. (M. 8463). It is the only one in w^hich the prominence marked aud. is shown, in consequence of the partial preservation of the inner portion of the periotic. In all the others the loss of the auditory bones leaves a large vacuity on either side of the basicranial axis, as above mentioned. A detailed account of the brain-cavity will not be attempted, and some of the more important characters only are here referred to. The olfactory lobes [ol.) are large, but not so large in proportion to the rest of the brain as in the Amblypoda. The cerebral hemispheres (A.) arc far more developed than in that sub- order, the frontal region being especially prominent and rounded. The surface of the cast is almost smooth, and in the absence of a distinct rhinal fissure it is difficult to say what portion of the cerebrum belonged to the neopallium. The only trace of a sulcus seems to be that marked s., running upwards and backwards on the side of the brain from behind and beneath the olfactory lobes. 16 TEHTIAEY VEETEBEATA OF TJIE EAYtjM. 'The optic nerves leave the skull far forwards, perforating the orhitosphenoids by two diverging ])assages, the inner openings of which lie close together at the bottom of a fossa (text-fig. 5, ii.) bounded anteriorly by a transverse ridge. Immediately ('xternal to and slightly below the level of the openings of the optic nerves there is a Text-fig. Cast of cranial cavity of Arsinoiiherium zitteli : A, from a))ove ; B, from below ; C, from left side. aud., auditory nerve-root ; ch., cerebellum ; f.ha., nerves passing tbrough foramen lacerum anterius ; h., cerebral hemispbere ; l.l., lateral lobe of cerebellum ; ol., olfactory lobe ; s., sulcus ; ii., optic cbiasma. g nat. size. large vertically elongated opening (represented by the projection marked f.l.a. in the cast), the anterior aperture of which {foramen lacerum anterius or foramen sphenoidale) is just over the alisphenoid canal, as described above (see text-fig. 4, ii. and f.l.a.). AKSINOITIIEIIIUM. 17 llehiiul and at a slightly higher level there is in the cast another prominence {and.), which probably marks the position of the exit of the auditory and perhaps also of the facial nerve. There is no condylar foramen, and consequently the cast shows no trace of the hypoglossal nerve. No clearly defined sella turcica is present, as the wliole of the surface of the basicranial axis is flat or slightly convex from side to side. I'he central portion of the cerebellum {ch.) seems to have been small and flattened : the limit between it and the cerebral hemispheres is marked by a slightly developed tentorial ridge. Laterally the cranial cavity is prolonged into a pair of large fossae, which may have been wholly or in part occupied by the lateral lobes of the cerebellum [l.L). This brain is larger in proportion to the bulk of the animal than in the Amblypoda, and seems to be fairly well developed for an Eocene Ungulate. At the same time it should be noted that in the earlier and contemporary genus Moeritherium the brain is relatively very much larger (see below). Upper Permanent Pentition. — The teeth of Arsinoitlierium (Pis. I.-V. ; text-hg. 6) form perhaps the most extraordinary dentition found among the Ungulates, and the interpretation of the peculiar structure of the molars which is here given must be regarded as provisional until it is either confirmed or destroyed by the discovery of earlier members of the group, in which the moditication of the teeth from more ordinary types is less extreme. The modification of the individual teeth has not been accompanied by any 3 1 4 3 reduction in their number, the dental formula being i. ^ c. p pm. m. 3, and, except for a short interval between the median incisors in the upper jaw, the teeth form a closed series and wear to a common level throughout. The most striking character- istics of the dentition as a whole are the extreme hypsodonty of the teeth (at least for an Eocene mammal) and the great difference between the molar and premolar teeth f text-fig. G). Tdie upper molars (PL V. figs. 6-8; text-fig. 6, A) are remarkable for the great height of their crowns and for the considerable changes of pattern their grinding-surfaces undergo in the course of wear. Each tooth consists essentially of two high transverse crests or columns {p.c. and a.c.), which posteriorly are slightly convex from above downwards and concave from side to side, while anteriorly they are convex in the latter direction. The posterior column is not situated immediately behind the anterior column, but a little towards the inner side, so that its outer edge is nearly opposite the middle of the anterior column (PI. V. fig. 6). Externally the two columns are completely separated by a deep vertical cleft, but internally they are only divided for a short distance in the upper part of the unworn crown, being united beneath this by a strong crest which seems to belong to the cingulum (c.'j. This cingulum is D 18 TEIOTTAET VEETEBRATA OF THE FATtjM. also strongly developed as a prominent crest (c.) in front of the inner half of the anterior column, from which it is separated by a deep fossa, and there is a trace of it on the inner face of the posterior column. On the inner side of the tooth tlie enamel ceases just beneath the cingulum, but on the outer and posterior sides the enamel-covered surface is greatly deepened, so that in a tooth in which the almost unworn posterior column is 11 cm. in height (PI. V. figs. 6 a, 6 b) the enamel-covered portion of the crown is only about 3 cm. deep on the inner side, while on the outer it is some 8 cm. in depth, and the posterior face of the posterior column is covered from base to crown (f 1 cm.). Wear commences at the summit of the anterior column, giving rise to a transversely elongated surface. Next the summit of the posterior column wears to the same pattern : at this stage the tooth appears as Text-fig. 6. Semi-diagranimatie figure of the iip])er aud lower teeth of the left side of Arsinoltheriuin aiulreivsi : A, upper teeth ; B, lower teetli ; C, outer view of last upper molar. «.(•., anterior column of molars ; c., anterior portion of cingulum ; c.’, posterior portion of cingulum; posterior column of molars. About j nat. size. an extremely hypsodont bilophodont type. Later the wear on the inner side reaches the level of the cingulum and the surface resulting from the abrasion of the anterior crest of the cingulum joins that of the anterior main column, at first internally only, but afterwards externally also, enclosing with it a deep enamel-lined fossa (PI. V. fig. 7). At the same time the posterior ])ortion of the cingulum comes into wear : its surface is at first continuous with that of the posterior column, but later with the anterior also, so that at this stage a continuous inner wall is established and the tooth ARSlNOlTllElllUM. 19 ])reseiits somewhat the pattern of a reversed molar of some sucli type as that of Ijophiodon or Tapirus (PL V. fig. 7). At this stage of wear the inner face of the tooth is covered with cement only, the enamel, as already mentioned, ceasing just below the cingulum on that side, while externally it continues to a much lower level. In the latest stages all that remains of the enamel is found on the posterior and external surfaces of the main columns, round the pit marking the last remnants of the main transverse valley and round that lying between the anterior crest of the cingulum and the anterior main column (see PL V. fig. 8). It is by examining the molar in its latest stages of wear, which give a section of the basal part of the tooth, that some explanation of its peculiar character may be arrived at. In this condition (PL V. fig. 8) the crown is seen to consist of an outer wall uniting the transverse crests, which are likewise joined at their inner ends, while in the middle they are separated by the remains of the main transverse valley: there is also a remnant of the fossa lying between the anterior main column and the anterior crest of the cingulum. From the appearance of the outer wall it seems probable that the brachyodont tooth from which these hypsodont molars have been derived had an ectoloph composed of well-developed parastyle and mesostyle, together with the antero-external and postero- internal main cusps, the inner portion of the tooth being constituted by the antero- internal and postero-internal cusps, which tended to unite with the antero-external and postero-external cusps respectively to form a pair of transverse ridges. The ectoloph was deeply infolded in front of the mesostyle, and, as the height of the tooth increased, this fold deepened rapidly till the tooth became nearly divided into anterior and posterior columns. If this interpretation be correct, the anterior column includes parastyle, antero-internal and antero-external cusps, while the posterior consists of the mesostyle, postero-internal and postero-external cusps. The form of tooth from which these molars were derived was probably much like that of the Hyracoids, in which the styles are strongly developed and the ectoloph is deeply folded. Moreover, as will be shown, there is a strong tendency in the early forms of that group for the teeth to form a continuous series. These peculiarities may be in themselves of little importance, but they suggest that possibly Aminoitlienmn and the Ilyracoidea may have originated from a common stock at some remote period. At any rate, both seem to have arisen in the same region. The roots of the molars (PL V. fig. 8 a) consist of a pair of transverse plates {p.r. and «.r.) extending the whole width of the anterior and posterior borders of th.e tooth, and a much smaller and shorter root (m.r.), imperfectly divided into two and situated on the inner border of the tooth between the inner ends of the main roots. These latter seem to remain open for some time after the crown has come into w^ear, so that the tooth is on the way to become rootless and permanently growing. The anterior main root appears to support the parastyle, the antero-external main cusp, and the antero-internal crest of the cingulum. The posterior root supports the D 2 1^0 TERTJAET YERTEBRAT^V OF THE FAYtM. wliole of the posterior column, tliat is, according to the interpretation here adopted, the mesostyle, the postcro-external and postero-internal cusps. The small inner root is imperfectly divided by a vertical groove into a larger anterior portion supporting that ])art of the anterior main column homologous with the antero- intcrnal main cusp, and a smaller posterior portion supporting the portion of the cingulum {c.') which in wear unites the inner ends of the main columns. Tlie premolars (PI. V. figs. 2, 3) present a sharp contrast to the molars, their strikingly different appearance being due to the presence of an almost fiat outer wall which shows scarcely any trace of folding. Like the molars they attain a high degree of hypsodonty, particularly on their outer side, where the enamel-covered portion of the crown is almost four times as high as on the inner side (PI. V. fig. 3 a) : in consequence of this, as in the case of the molars, these teeth are strongly curved, the concave face being turned towards the palate (text-fig. 3, p. 11). The ectoloph is fiat or at most gently concave from before backwards, and it appears to be composed of three elements. Of these, one forms the antero-external angle of the tooth and is connected with the cingulum on the anterior face of tlie tooth, so that it may be regarded as a parastyle The element behind this is a large cusp (ae.) widened out transversely as it wears down, so that eventually it forms a junction Avith tlie cusp («?’.) internal to it. Behind this main outer cusp is a smaller one forming the postero-external angle of the tooth. The anterior face of the tooth is occupied by a prominent crest of the cingulum (c.), which dies away internally, Avhile externally, as already mentioned, it is eonnected with the parastyle. On the inner face of the tooth there are two elements {ai. and ju.), the anterior of Avliich is the larger. This becomes connected Avith the antero-external cusp, forming a transverse crest, and at the same time it is united by a ridge Avith the postero-internal cusp. In still later stages of Avear this postero-internal cusp becomes united Avith the postero-external, so that finally the centre of the tooth is occupied by an enamel-lined pit enclosed by the continuous Avear-surfaces of the outer and inner pairs of cusps and tlie connecting transverse ridges (PI. V. fig. 3). The three posterior premolars have two roots, one anterior the other posterior, each extending the Avhole Avidth of the tooth : the division betAveen the roots is much deeper on the inner than on the outer side (PI. V. fig. 3 a). The anterior premolar is simpler than the others, having only one root. It is closely crowded between the second premolar and the canine, Avhich it much resembles, being a simple curved columnar tooth. The canine (PI. V. fig. 1) and the tAvo posterior incisors are similar and are also closely croAvded together. On their inner face there is a prominent cingulum enclosing with the croAvn a deep fosette. The anterior incisor, judging from its alveolus, is iiiucli larger than the others. In no specimen has this tooth been found in sifn, but an isolated examjile almost certainly referable to this position has a curved and pointed croAvii Avith a shelf-like AliSINOrniElilUM. 21 jn’ojcction of tlic cingulum on its inner side. This tooth must have projected somewliat below the others, and was separated from its fellow of the opposite side by a considerable interval (about 2‘5 cm. in the figured skull). Upper Milk-dentition. — The upper milk-dentition is imperfectly known. The most nearly complete specimen of what may be regarded as the upper milk-molars is figured on PI, V. fig. 5 (also text-fig. 7). Mm. 4 is precisely similar in structure to the permanent molars, though much smaller. Its anterior column is immediately beneath the hinder border of the antorbital foramen. It is only slightly worn, so that the anterior crescent (c.) of the cingulum is not yet reached. M?n. 3 is also much like a permanent molar, but the compound character of the anterior column is much more clearly shown than in the molars; it consists of an outer portion, probably equivalent to the parastyle and the antero-external main cusp, and an inner portion, the antero-internal main cusp. The form of the posterior enamel-covered surface of Semi-cliagrammatic figure of the upper luilk-niolars of ArsinoWierium zilteli. (I.C., anterior column ; a.e., antero-external cusp ; c., anterior part of cingulum ; c.', posterior part of cingulum ; ^nc., postei’ior column ; jo.e., postero-external cusp. About ^ nat. size. the column apparently shows a stage in the infolding of the ectoloph to which the origin of the peculiar bilophodonty is ascribed above. In mm. 2 the ectoloph is complete, and is only slightly concave, but it can be seen how a slightly deeper infolding would give rise to a tooth like mm. 3. The inner part of the tooth consists of two transverse crests, and in front of these a ridge of the cingulum, which with the anterior crest encloses an enamel-lined pit as in the other teeth. The antero- internal tubercle is large and tends to unite in wear with the postero-internal, so as to form an inner wall similar to that found in the permanent molars. The first milk-molar is not shown in the figure on PI. V., but is included in text-fig. 7. Its outer wall consists of parastyle, antero-external and postero-exteimal elements. On the inner face there is a trace of an antero-internal element only, but the cingulum (c.) is very strongly developed, particularly posteriorly, where together with the ectoloph it encloses a deep enamel-lined fosette. The milk-incisors are simple conical teeth. TERTIAEY VEETEBEATA OE THE EAY&M. 0 9 Mm\(TMe. — The sym])liysis of the mandihle (PI, IV. figs. 1, 3, s.) is long, and its ventral snrfaee is divided into two regions — an anterior rounded portion sloping back from the incisor alveoli, and a posterior portion which is flattened and is in the same line as the ventral surface of the lower border of the horizontal rami, making an obtuse angle with the anterior region. In the middle of this flattened portion there is a small rugose tuberosity for the attachment of muscles, and the dorsal surface forms a narrow s]iout-like channel. The length of the symphysis seems to have increased with age, at any rate the relative position of its posterior angle with regard to the teeth alters. Thus ill a young mandible in which the last molar is being cut, the hinder angle of the symphysis is beneath the posterior lobe of pm. 4, while in another fully adult it is beneath m. 2 : there seems, however, to be considerable individual variation in this matter irrespective of age. The horizontal ramus is comparatively narrow from above downwards : it widens out a little beneath the last premolar, and gradually narrows beneath the molars. The alveolar border is slightly convex from before backwards, and its inner edge, at least in the molar region, is higher than the outer. The ventral border is slightly convex from before backwards, and strongly so from side to side. The inner faces of the rami are nearly flat, the outer convex. The two rami are separated from one another by a narrow interval, and are nearly parallel as far back as the last molars, but behind this they diverge considerably. The single mental foramen is beneath the fourth premolar. The angular region (a.) is separated from the ventral border of the horizontal ramus by a slight concavity : it is rounded and its posterior edge is thickened so as to form a broad surface, looking backwards and somewhat outwards. Superiorly it is bounded by a sharp angle which projects considerably behind the condyle, from which it is separated by a concave border about 8 cm. long. The condyle (cd.), which is elongated from side to side, is set somewhat obliquely, and is slightly convex from side to side, rather more so from before backwards. It is supported on either side by a rounded thickened ridge, and in some cases it is divided by a slight median notch into an outer and an inner lobe, which are subequal. The posterior border of the corouoid ])rocess rises immediately in front of the condyle, and in the specimen described its pointed upper end is about G cm. above the articular surface. The anterior border of the corouoid is convex and ])asses by a gentle curve into the horizontal ramus, its edge dividing into two ridges, which becoun' continuous below with the outer and inner edges of the alveolar border respectively , so that in this region the mandible is quite unlike that of a I’roboscidean, in which the corouoid arises on the outer face of the horizontal ramus in advance of tlu' hinder end of the last molar. Tlie jaw further diflers widely from that of a Proboscidean in the form of the symj)hysial region and in the presence of a closed series of incisor, canine, and cheek-teeth : in both the Proboscidea and in Ikiryther'mm the incisors are modified to form procumbent tusks, and there is a long diastema. AltSlNOlTJlEEIUM. 23 The mandible differs from that of tlie Dinocerata in being more massively built, in the absence of downwardly directed flanges of bone, in the absence of a diastema, and in the much greater depth and different form of the posterior })art of the jaw. Lower Lennanent Dentition. — Although in no specimen are the teeth perfectly preserved in the front of the mandible (PI. IV. figs. 1, 3 ; and text-fig. 6, B), it can be determined with certainty that the dentition was complete (^. 3, c. 1, pm. 4, 3). The teeth all have high crowns, wear to a common level, and form a closed series, the median incisors being in close contact with one another in the middle line. The molars, like those of the upper jaw, are extremely hypsodont, especially on their outer side, where the enamel-covered portion of the crown is much higher than on the inner side. The unworn molars are bilophodont (PI. V. fig. 4), consisting of two high narrow transverse crests, which are connected by a much lower oblique crest running from the summit of the outer end of the posterior column to the base of the inner end of the anterior column. A similar ridge also runs from the outer end of the anterior column forwards and inwards, forming the anterior border of the tooth, and enclosing with the anterior face of the front column a shallow depression. The tooth may, in fact, be regarded as composed of two V-shaped columns, the posterior limbs of the V’s being placed transversely and being much thicker and higher than the comparatively slightly developed anterior limbs. In wear this structure becomes more obvious. The anterior face of the transverse crests (that is, the sides of the V’s facing inwards) is covered by very thin enamel, differing entirely from that coating the outer side of the tooth. In the last molar the talon is represented by one or two irregular, small, but prominent cusps. The cingulum is well developed on the posterior face of the molars, where it forms a distinct shelf-like projection. The phases of wear in the molars are, seen in PI. IV. figs. I, 3. In m. 3 the two main columns are shown with the anterior arm of the front V just in wear and enclosing a shallow fossa in front of the tooth. In the next the anterior arm of the posterior V is strongly worn, and the anterior fossa just referred to has been completely lost on the right side, but is still represented on the left by a small island of enamel. In both these teeth the inner face is still covered with enamel, though the covering is much thinner than on the outer side. In m. 1 the inner side of the tooth has already been worn down below the level of the crown, so that the enamel is there wanting. The divisions between the two arms of the V’s have now quite disappeared, but the outer ends of the two main columns are still separated by a fold of some depth, Avhich also disappears when the tooth is a little more worn. The inner edge of the teeth is considerably higher than the outer, in correlation with the opposite condition in the opposing upper molars. The premolars differ greatly from the molars, their crowns being much narrowe 24 TEIITIAIIT VERTEBliATA OF THE FAYtTM, (see text-fi<4‘. (i, ]). 18) ; at the same time tlie difference is less than that between the ii])j)er ])rem()lars and molars. They are four in number, the three posterior ones being- double-rooted. 7bn. 1 is not known in A. zitteli, but in A. andrewsi its crown is very like the others ; in both species it has a single root. Each premolar consists of twf) columns separated externally by a deep vertical groove. In early stages of wear the pattern is a double V, but later the concavity of the V’s becomes obliterated, and the inner face of the teeth is nearly straight. In some unworn specimens the postero-internal end of the anterior V is seen to project somewhat across the opening of the posterior V so as partially to close it : this projection seems to correspond with the metastylid of some other ungulate teeth (e. g. llyrax \^Frocavi(i'\, Equus). The cingulum is well developed on the inner face of the teeth, and is also present in some specimens, though not all, on the outer side between the main columns. The closely ci'owded canines and incisors are, so far as known, closely similar to one another. They are high columnar teeth, convex outwards from above downwards, and nearly rectangular in section. The outer face of the crown is strongly convex from side to side ; on the inner side the cingulum is well developed, and between it and the inner face of the tooth there is a deep, more or less developed pit or “fosette.” The lower milk-dentition is imperfectly known, and in such specimens as are preserved it appears tliat the milk-molars are practically identical in form with the molars of the permanent series. Vertehral Column. — In correlation with the great size and weight of the skull the atlas (text-fig. 8) is very large and massively constructed, its width being especially great. The condylar cups {cond.) are large and widely separated both above and below ; they are strongly concave from above downwards, and are much wider above than below, where they narrow rapidly as they pass on to the ventral bar. 'fhe lateral surfaces for the axis {ax.) consist of a subcircular, slightly concave u])per portion, from the outer and lower side of which a less well-defined triangidar area runs down to the ventral bar, nearly reaching the outer border of tlie odontoid face {od.). This is very broad, sharply defined, slightly concave from side to side, and ])rolongod somewhat backwards on a median prominence of the ventral bar, the posterior- angle of which forms a blunt hyjrapophysis. The neural arch is wide both from side to side and from before backwards ; its up])er sin face is strongly convex from before backwards and forms a slight prominence on either side of the middle line (rr.s“.). Laterally, close to its anterior border, the arch is perforated by the narrow slit-like passage which transmits the first s])inal nerve [sp.f.). This foramen opens into a groove, the posterior border of which forms the anterior edge of the large transverse process {t.p.). This is very AESlNOITHElilUM. 25 large and massively constructed ; anteriorly it is bounded by the sharp border just mentioned ; posteriorly, on the other hand, it has a broad flat surface, and it is perforated near its base by the vertebrarterial canal [f.tr.). Its outer ends form broad, roughened, rather convex surfaces. Text-fig. 8, Ax4 ns. Atlas vertebra of Arsinoitherium zitteli : A, from back ; B, from front ; C, from above. nx'., lateral surface for axis ; cond., surfaces for occipital condyles ; f.tr., vertebrarterial canal ; n.s., neural spine ; od., surface for odontoid process ; sp.f., foramen for first spinal nerve ; t.p., transverse process. 4 nat. size. This atlas differs from that of the Dinocerata in being much wider, and in having longer transverse processes and a less convex neural arch. From the atlas of Elephas it differs in its much longer transverse processes, less convex arch, less developed spinous tuberosities, and smaller vertebrarterial canal. In E 2G TERTIARY VERTERRATA OF THE FAYtM. Elephas also the upper ends of the surfaces for the axis project inwards so as to form a constriction of the opening of the vertebra, separating the neural canal from the lower ])art occupied by the odontoid process of the axis. In the axis vertehra (text-fig. 9) the odontoid process [od.p.) is blunt and rounded, and its base extends from the upper to the lower surface of the centrum. Its extreme end is rounded, with a slight ridge on its upper surface. The posterior lialf of its lower surface is occupied by a sharply-defined surface for articulation with the ventral l)ar of the atlas [v.fac.) ; this surface is gently convex from side to side. On either side of the odontoid there is a deep groove separating it from the main surfaces of articulation for the atlas [at.). These are roughly triangular in outline, the angles being rounded ; they are inclined to the long axis of the column at an angle of about 45°, and are gently convex except close to the inferior Text-fig. 9. Axis vertebra of Arsinoitherium zitteli : A, from front ; B, from right side. at., surface for atlas vertebra ; n.sp., neural spine ; od.j)., odontoid process ; p.s., posterior zygapophyses ; t.p; diapophysis and parapopbysis forming transverse process ; v.c., vertebrarterial canal ; v.fac., ventral facet of odontoid process. I nat. size. angle, where there is a slight concavity. The upper edges of these atlantal surfaces are separated from the base of the neural arch by a deep groove. The pedicles of the arch are wide, and its upper portion is very massive ; the neural spine [n.sp.) is represented by a great tuberous mass of hone, which forms a single median prominence on the front of the arch, but posteriorly is divided into two by a large median depression. The posterior zygapophyses {p.z.) are large ; their upper surface is roughened, and their articular facets consist of a larger, nearly circular, outer portion, looking nearly directly downwards, and a smaller inner face looking inwards and downwards. The posterior face of the centrum is very large, and its up])er border sometimes forms a prominent rim rising somewhat above the level of the rest of the upper surface. It is very slightly concave and is oval in outline, with its AllSINOlTIIEElUM. 27 ventral border produced downwards into a pair of blunt hypapopbysial prominences. The transverse process {t.p.) is perforated by a vcrtebrarterial canal [v.c.) ; the dorsal bar is slender and is continuous above with the outer edge of the neural arch ; the ventral bar is much larger, and its base is elongated so that it arises from almost the whole length of tlie side of the centrum. From the large series of vertebrae preserved in the Museum at Cairo it has been possible to make up a set of cervicals with some degree of certainty ; at the same time, owing to the great variability in size of the animals from which they were derived and the circumstance that so far no associated specimens have been found, the following account of the successive vertebrae must be taken as provisional, and subject to revision if at any time an associated series should become available for description. The most notable characteristic of the cervicals as a whole is the shortness of their centrum compared to its great width and height. The neck must have been as short and massive as in the Elephants, and the movements of the head much restricted. In the third cervical (text-fig. 10, A) the centrum is roughly quadrate in outline with broadly rounded angles. Its neural border is nearly straight, and the ventral surface bears a pair of blunt hypapopbysial ridges. Both the anterior and posterior faces are slightly concave, and the body is very short in proportion to its width and height, the length (thickness) of the middle of the centrum being only 3‘3 cm., while its width is 13'6 cm. and its height 11 cm. The pedicles of the neural arch are stout, but its upper portion is thin, except towards the summit, where a W-shaped thickening represents the neural spine {7i.sp.). The zygapophyses are large and their articular faces nearly fiat. The anterior zygapophyses {a.z.) bear on their outer side blunt metapophyses. The vertebrarterial canal (v.c.) is enclosed by a comparatively thin diapophysis (dp.) above and a much stouter parapophysis {pp.) below. This latter arises from the lower part of the side of the centrum. After enclosing the canal these processes again diverge into a small upwardly projecting process and a much larger one which is directed downwards and backwards. The fourth cervical (text-fig. 10, C, D) is much like the last, except that (1) the arch slopes a little forwards, (2) the spine is higher, (3) the diapophysial bar of the vertebrarterial canal is wider and straighter. The fifth cervical (text-fig. 10, B) is generally similar to the fourth, but differs in the following respects : — (1) the upper part of the arch is more slender and slopes more forwards, (2) the diapophysis is still larger and ends in a large tuberosity, (3) the vertebrarterial canal is smaller and rounder, (4) the ventral process of the transverse process (tp.) is much elongated and projects considerably below and behind the centrum. The sixth differs from the last in having shorter parapophysial processes. A E 2 28 TERTIARY VERTEBRATA OF THE FAYtTM. pair of hypapoj)liysial ])roininences is jireseiit, and the neural spine is represented by a W -shaped thickening. In the last cervical (text-fig. 10, E) the slightly biconcave centrum is still short, somewhat more so dorsally than ventrally ; it is oval in outline. The neural spine is represented by a blunt ridge. Behind the pedicle of the neural arch there is a deep groove running down from the neural canal behind the transverse process, which is here imperforate and has a blunt tuberous extremity. On the Cervical vertebrae of Arsinoitherhim zitteli : A, third cervical, from front; R, fifth cervical, from front; C, fourth cervical, from front ; D, ditto, from right side ; E, seventh cervical, from front. a.z., anterior zygapophyses ; dj)., diapopliysial bar ; hp., hypapojdiyses ; 7i.sp., neural spine ; pj^., ])arapo- physial bar ; p.^., posterior zygapophyses ; tp., transverse processes ; v.c., vertebrarterial canal. nat. size. hinder border of the centrum near its ventral angles is a jtair of facets for tlie heads of the first ])air of ribs. These facets are continuous posteriorly with the posterior face of the centrum and look outwards, backwards, and downwards. The thoracic series is not completely known. In the anterior region (text-fig. J 1 ) the centrum is wider tlian high ; its anterior face is flat, while the posterior face is ARSINOITlIEIilUM. 29 slightly concave. The transverse processes are large knobs with rib-facets {t.j .) on their antero-lateral surfaces. The anterior zygapopliyses {a.z.) are placed very low, little above the level of the top of the centrum. The neural arch rises into a high backwarclly directed neural spine (n.sj).), the anterior face of which is formed by two Text-fig. 11. A X i B X -1 Anterior thoracic vertebra of Arsinoitherium zitteli : A, from front ; B, from right side. a.z., anterior zygapophysis ; c.f., capitular facet ; n.sp., neural spine ; p.z., posterior zygapophysis ; t.f., tubercular facet. 5 nat. size. Text-fig. 12. Middle thoracic vertebra of Arsinoitherium zitteli : A, from front ; B, from right side. Lettering as in text-fig. 11. | nat. size. surfaces meeting at a sharp angle, while the posterior face is concave ; towards the summit the spine tends to become bifid. The anterior capitular facets {c.f.) are placed low down on the sides of the centrum, the posterior ones higher up. Further back in the series (text-fig. 12) the body of the centrum becomes 30 TEliTrARY VEUTEERATA OF Till-] FAYOM. deeper, while the oval capitular facets {c.f.) are higher up and partly borne on the base of tlie arch, the anterior being somewhat lower than the posterior. The transverse ])rocesscs are larger and more massive, and each bears a well-marked tubercular facet {t.f.) on its outer end. The neural spine is very high and broad ; it slopes strongly backwards, and its anterior face is convex from side to side, while its posterior is deeply concave. The anterior border of the neural arch is deeply concave from side to side, so that in a dorsal view of the vertebra much of the neural surface of the centrum is exposed. At the same time the arch overhangs the posterior border of the centrum to a great extent. The anterior zygapophyses [a.z.) are mere shelf-like surfaces on the anterior border of the arch, and the posterior zygapophyses (jf.z.) form facets on the lower surface of the posterior border. In the posterior thoracic (text-fig. 18) the spine (n.sjj.) is a low and backwardly- directed crest, and, as in the middle region, the anterior border of the arch is very Posterior tlioracic vertebra of ArsinoiiJierium zitteli : A, from front ; B, from right side. Lettering as in text-fig. 11. 5 nat. size. concave, while the posterior border overhangs to a corresponding extent. The anterior zygapophyses {a.z.) are now concave from side to side, and external to tliem there are prominent metapophyses connected by a ridge wdtli the stout, somewhat backwardly-directed, transverse ])rocesses. The outer ends of the transverse processes bear small tubercular facets {t.f.). Tlie ])ost('rior zygapojihyses {p.z.) are prominent and convex from side to side. Tlie capitular facets {c.f.) are nearly circular and are borne on short jirocesses rising from the side of tlie neural arch above the level of the neural surface of the centrum. Still further back the centrum is deeper in ])roportion to its width, and the transverse jirocesses are more prominent and less massive, while the neural arcli is still lower. !n the lumbar region the vertebra; become much depressed, till in the hinder ARSrNOlTIIEEIUM. 31 portion the centrum may bo nearly twice as wide as it is high ; at the same time it becomes somewhat more elongated. The neural border of the centrum is straight and the neural arch is low and wide. The zygapophysial surfaces are cylindrical and the neural spine is low and projects considerably behind the centrum, while at the same time the anterior border of the arch leaves the anterior half of the neural surface of the centrum exposed. The transverse processes are broad from before backwards, and in the anterior region they are narrow from above downwards, but as they are followed backwards they become larger and more massive. In the whole of the large collection of vertebrae in the Museum at Cairo there is not a single example of the sacrum, nor does any such occur in the collection in the British Museum. On the other hand, there are a considerable number of vertebrae of the form shown in text-fig. 14: these greatly resemble the lumbar vertebrae, except that the lateral processes are very large and massive, and bear at their extremities broad, roughened, nearly triangular surfaces (il.s.), apparently Sacral (?) vertebra of Arsinoitherium zitteli : A, from front ; B, from right side. a.Z; anterior zygapophysis ; n.s^j., neural spine ; il.s., iliac surface. a.z. Text-fig. 14. for union with the ilium. These vertebrae are believed to be the anterior sacrals. Another somewhat different type was probably the second sacral : in this the centrum is even more depressed than in the last, and its ventral surface is almost in the same plane as the ventral surface of the lateral processes, which are very long and terminate in a surface which looks somewhat backwards. The fact that, so far as at present known, the sacrals do not unite as usual to form a sacrum is especially remarkable in an animal of such size and weight. Of course, it is possible that a true sacrum may yet be found, but considering the usual solidity of that structure it is very curious that in so large a collection no specimen should occur, while a score or more examples of the atlas and axis have been obtained. The anterior caudals have a very depressed centrum, with broad, flat, rather long, transverse processes. The neural arch is low and situated on the posterior half of the centrum. Further back the caudal centra become more cylindrical, with short TEliTIARY VERTEBRATA OF TITE EAYtTM. r,2 transverse ])r()cesses situated near their anterior end. In the anterior caudals the anterior and ])osterior faces of tlie centrum are inclined backwards. d'lie exact numher of vertehne in the different regions of the vertebral column is as yet unknown. A considerable number of scattered I'ihs have been found. The anterior ribs are short and expand below into a large blade. 'J'he articulation is double and the capitular surface has distinct anterior and posterior facets. In the mid-dorsal region the head is large and prominent; here also it has two facets making an obtuse angle witli one anotlier, the anterior being the smaller. The tubercle is comparatively small. The blade is flat behind and convex in front, with a slight groove along the inner (anterior) margin. The sternum is unknown. Fore Limh. — The general form of the scaimla is shown in text-fig. 15. It will be seen that the prescapular fossa is much smaller than the postscapular: it is about the same width throughout, owing to the fact that the anterior (coracoid) border {c.h.) of the bone is nearly parallel with the spine (s.). The postscapular fossa is very large : anteriorly, it is gently concave and is overhung by the spine which slopes somewhat backwards ; towards the suprascapular border (s's.^.) the surface is somewhat convex. The upper part of the coracoid border {c.h.) is slightly convex and is separated by a deep bay or notch from the coracoid process (c.). The suprascapular border {ss.h.) consists of two convex portions, the smaller anterior one being over the prescapular fossa, the larger posterior over the postscapular; the two are separated by a shallow concavity above the origin of the spine. The upper posterior angle of the bone is prolonged considerably backwards and is rounded. The glenoid border {q.h.) is concave, becoming more deeply so towards the glenoid cavity {g.c.). The coracoid process {c.) is stout and blunt, and is not separated from the anterior angle of the glenoid cavity, the articular surface running on to its posterior face. 'The glenoid cavity {g.c.) is an elongated oval (text-fig. 15, II), the long axis of which is antero-posterior, in which direction it is deeply concave, forming nearly a quarter of a circle. Transversely there is scarcely any concavity, so that the articulation with the humerus is almost cylindrical (see description of the head of the humerus given below). 'I'he spine (6‘.) arises close to the superior border, and increases gradually in height tfjwards the glenoid cavity, about three centimetres above wdiich its base terminates, 'file superior border of the S])iue is prolonged down^vards into a blunt acromion ])rocess {a.) which slightly overhangs the glenoid cavity. The end of this ])rocess, and indeed the whole of the free edge of the spine, is thickened and roughened. As a whole, tlie spine is inclined somewliat backwards. 'The su])rascapular border is completed by an epiphysial cap, much roughened and rounded externally. The inner face of the sca])ula (suhscapular fossa) is concave in front of, and behind. AESINOTTIIEEIUM. O t> oo the line marking the base of the spine, a little in advance of which there is a roughened ridge. In some specimens there are two or three rough parallel ridges on the inner face of the bone, apparently corresponding with the ribs, or with the intervals between the ribs, against which the bone rests. The scapula of Elephas differs from that just described in the following points : — (1) the extreme narrowness of the prescapular fossa ; (2) the presence of a Text-fig. 15. Left scapula of ArsinoitJierium zitteli : A, outer face ; B, articulation. a., acromion ; c., coracoid process ; c.h., coracoid border ; g.h., glenoid border ; g.c., glenoid cavity ; s., spine ; ss.h., suprascapular border. \ nat. size. backwardly projecting process on the middle of the spine ; (3) the sharp angulation of the suprascapular border above the origin of the spine, the portion of the border above the prescapular fossa being inclined to the portion above the postscapular at an angle of about 100 degrees ; (4) the totally different form of the coracoid border and coracoid process. In the scapula of Uintatherium the postero-superior angle is not produced F 34 TEllTIAET VEETEBKATA OF THE FAT&M. backwards as in the ])rcscnt s])ecimcn ; moreover, as in the Elephant, the supra- scapnlar border is sharply bent above the origin of the spine, the portion in front making an angle of Go degrees with that behind. The coracoid process is also quite dissimilar, while the spine inclines forwards rather than backwards and the prescapnlar fossa is smaller. The humerus (text-fig. 16) differs very considerably both from that of Elephas and also from that of the Dinocerata. Its most striking general characteristic is the great antero-])osterior compression of its shaft and distal end. The head (/«.) is large and much more convex antero-posteriorly than from within outwards, so that it almost forms part of a cylinder. The head is most prominent posteriorly. The inner (lesser) tuberosity [l.t.) is small and its inner face flattened. The outer (greater) tuberosity {g.t.) is large and forms a very prominent crest projecting considerably in front, but is not continued down the face of the shaft as a well-marked ridge, such as occurs in Ulntatherium, nor is it so massive as in Elciilias. The bicipital groove {h.g.) is broad and not very distinct. Beneath it the shaft is strongly compressed from before backwards, and about the middle of its length it bears on its outer border a prominence (d.) formed by the great development of the deltoid crest for a short distance. From this prominence a short ridge runs obliquely across to about the middle of the shaft. The coronoid fossa (ostero- internal slope of which supplied a surface for union with the sca{)hoid (sc.). Most AllSINOITHEIlIUM. 45 of the rest of this surface articulated with the lunar [lu.], though, as above mentioned, a narrow strip on the outer side was probably overlapped by the cuneiform ; in no specimen of the magnum, however, have actual traces of this overlap been observed. The surfaces for the trapezoid on the one hand, and for the unciform [unc.) on the other, are similar : each consists of a facet which extends the whole depth of the bone in front, but is confined to the upper half posteriorly, the ventral portion of the posterior part of the bone being pinched up into a rounded and backwardly Text-fig. 23. B, X i., C. Left magnum of Arsinoitherium zitteli : A, unciform face ; B, from above ; C, from below. lu., facet for lunar ; me. 2, me. 3, facets for the second and third metacarpals : sc., facet for scaphoid ; unc., facet for unciform. | nat. size. projecting knob. The distal surface (me. 2 and me. 3) is nearly triangular, the posterior angle extending on to the narrowed posterior region just referred to. In some specimens a small area at the antero-internal angle (me. 2) of this surface is marked off from the rest, and indicates that the articulation of the second metacarpal, in some cases at least, extended slightly on to the magnum. The uncifoj'm (text-fig. 24) is a wedge-shaped bone, the base of the wedge being the inner surface articulating with the magnum (mag.), the facet for which is nearly flat and extends the whole depth of the bone in front, but is confined to the upper 40 YEKTEiniATA OE THE EAYtJM. lialf at ilie Ijac.k. 4'lic proximal surface for the cuneiform {cu.) is concave antero- ])ostoriorly and convex from side to side. Distally the bone bears two large surfaces for tlie fonrtli and fiftli metacarpals, and a much smaller inner surface for the outer facet of the slightly displaced third metacarpal. The surface for the fourth metacarpal is somewhat concave and looks directly downwards ; that for the fifth is convex and looks downwards and outwards, almost joining that for the cuneiform externally, making with it the acute angle which is the thin edge of the wedge. 'I'lie bone is deeper posteriorly than anteriorly. The mctacarpah (text-fig. 19, jv 4 0) rvere short and stout and much enlarged at their articidations. I'lie first is unknown, but, judging from the size of the distal articulation of the sca})hoid, probably little reduction had taken place on this side of the foot. Text-fig. 24. Left uncifonn of ArnliwWicriiim ziltdl : A, from above; B, from below; C, inner (preaxial) face. cu., facet for cuneiform ; mail., facet for magnum ; me. .4, me. 4, me. A, facets for the tliircl, fourth, and fiftb metacarpals. 5 nat. size. The second is likewise unknown, but it had on its postaxial side a small surface for articulation tvith the magnum, as is shotvn by the presence of the corresponding facet on that bone. The third articulated mainly xvith the but had a slight overlap on the viidform at least anteriorly, d'he fourth and fifth articulated with the unciform, and in some cases (c. fj., C. 7968) the fifth seems also to have liad a surface of contact with tlie evneifonn (text-fig. 25, cu.). d'he posterior face of the upper end of the metacar])als seems in all cases to be ])rodiiccd backwards into a strong roughened ])rominence. AKSlNOITIlElilUiM. 47 Hind liimh. — The best example of the pelvis is a complete s])ecimen in the Cairo Museum (C. 8413), and it is upon this that the following description and figures (text-figs. 20, 27) are founded. The ilia [il.) are immensely expanded bones, of which the gluteal surface is slightly convex exce]h towards the superior angle, which is somewhat everted so that the outer surface there becomes concave. The pelvic (inner) surface is slightly concave, except towards the upper border, where the everted portion just referred to bears a deeply hollowed surface for union with the sacral vertebrae. The superior angle formed by the meeting of the superior border [crista ilii, c.i.) with the posterior is almost a right angle. In front the crista ilii sweeps round into the anterior border, which is greatly thickened, broadly convex, and term'nates below in the prominent external angle [e.a.), which, like the superior angle, is capped by a large rough epiphysis, that on the lower angle [e.a.) being the larger. The acetabular border [a.h.) is concave, and just before reichiug the acetabulum [a.) Text-fig. 25. Fifth left metacarpal of Arsinoitherium zitteli. cu., svu’face of contact with cuneiform ; me. 4, facet for fourth metacarpal ; unc., facet for unciform. I nat. size. it is interrupted by a roughened notch, probably for the attachment of the rectus femoris muscle. The inner border running down from the superior angle is concave except in its upper portion opposite the sacral facet, where it is straight; a little above the level of the glenoid cavity it divides into an anterior ridge continuous below with the anterior edge of the pubis, and a posterior ischial ridge, which runs back to the ischial tuberosities. The surface between these two ridges is deeply concave. The acetabulum [a.) is oval, its long axis corresponding with the long axis of the os innominatum. The pit for the ligamentum teres is very deep and extends upwards beyond the middle of the cavity; posteriorly the pit opens on the ischial surface by a deep notch in the border of the glenoid cavity. The anterior border of the united pubes [pu.) is slightly concave, while the posterior 48 TERTIARY VEETEBRATA OF THE FATtM. Text-fig. 20. o., aceiabulum ; a.&., acetabular border ; c.?., crista ilii ; e.u., external angle of ilium ; is., iscbium; is.t., ischial tuberosity ; o.f., obturator foramen ; pubis ; sijm., symphysis. ^ nat. size. Text-fig. 27. Pelvis of Arsinoitlierium ('?)z{lleli, from right side. il., ilium ; other lettering as in last figure, i nat. size. ARSINOITIIKRIUJM. 40 bovdev of this bone vans up and becomes continuous with the inferior edge of th(‘ cotylar notch, the other edge of which is continnous witli the antero-inferior border of the ischium, so that tlie notch actually o])ens into the upper end of the obturator foramen. The angle of the ischial tuberosity (is.t.) is nearly right ; the border of the bone behind the angle and the angle itself are covered by a roughened e])iphysial cap. The hinder border of the united ischia is. slightly concave, and the bones themselves are flattened near the angle and rounded near the symphysis. Tin* pnbis is a broader thin bar of bone ; it is slightly concave above and convex below ; it widens out towards the symphysis [sym.). The obturator foramen (o./*.) is an elongated oval, the outer end of which, as already noticed, is continuous with the cotylar notch. The pelvis of UintatJiennm differs from that just described in the following })oints : — (1) the crista illi is much more convex in outline; (2) the surfaces for the sacral vertebrae are much more prominent and strongly marked; (3) the symphysis is less massive and the obturator foramen is wider ; (4) the ischia and pubes are rather stouter and the ischial tuberosities are more developed ; (5) there is a deep fossa on the visceral surface nearly opposite the acetabulum, whereas in Arsinoitheritmi this is only slightly marked. In Elephas the form of the ilia is more like that described and figured, but the pubes and ischia, particularly the latter, are much ■wider, so that the symphysis is much longer and consists of di^stinct pubic and ischial portions united by a narrow bar. One result of this is, that the ischial portion of the pelvis projects much farther behind the acetabulum than in ArsinoitJterium. In Elephas also the sacral surfaces are better marked and the ischial tuberosities more prominent. The femur (text-fig. 28) is remarkable for the great antero-posterior compression of the shaft and for the flatness of its posterior face, the outer border of which forms a thin sharp edge. The head (A.) is very large and nearly hemispherical ; it looks upwards and somewhat outwards, and its ])osterior border is crossed by a deep groove for the Ugamentnm teres [n.l.t.). The great trochanter {(/-t.) is compressed antero- posteriorly, and does not rise so high as the head; its posterior face is slightly concave, while anteriorly it forms a considerable rugose prominence. The lesser trochanter [l.t.) is inconspicuous and close beneath the head. The shaft, as already mentioned, is extremely compressed from before backwards, and its posterior- surface is nearly flat. The anterior face is convex towards the, inner side, but externally it is nearly fiat and meets the posterior surface so as to form a thin sharp outer border, which, near its middle point, is slightly convex, the convexity being apparently the representative of the third trochanter : the inner border of the shaft is rounded. The condyles (/.c., o.c.), which are relatively small, are subequal and are separated by a narrow but deep fossa [i.n.). Above the condyles H -00 TEUTTAET VEETEBRATA OF THE FAYtJM. Text-fig. 28. Eiglit femur o£ Arshioitlievium zittcli : A, from front ; B, from back ; C, upper end ; 1), lower end. greater troclianter; /n, head ; i.c., inner condjde ; i.v., intercondylar notch; it., inner tuberosity; L<., lesser trochanter; notch for Hrjurnmlum teres; o.c. outer condyle; o./., outer tuberosity; tr., troclilear surface. J nat. size. ARSINOITIIERIUM. 51 there is on either side of the bone a prominent tuberosity [i.t., o.t.). The posterior surface of the shaft immediately above the condyles is sliglitly concave from side to side, the concavity being bordered by ridges running upwards and inwards from the tuberosities. The lower end of the bone is much narrower than the upper end. The femur of Uintatherium differs in the following points: — (1) it is not so much compressed from before backwards, and at the same time it is considerably narrowed from side to side near its middle ; (2) there is a small but prominent lesser trochanter ; (3) the hinder surface of the great trochanter is hollowed by a digital fossa ; (4) the distal articular end is relatively larger. The femur of Eleplias differs from that just described in the following points : — (1) the neck is much longer; (2) the great trochanter does not rise nearly so high and its posterior face is excavated by a deep digital fossa; (3) the shaft is not compressed to anything like the same degree, and its posterior face is not so much flattened ; (4) the distal articulation is relatively larger. Text-fig. 29. Riglit patella of Arsinoitherium zitteli ; A, from inner side ; B, from articular face, inner surface for femur ; o., outer surface for femur ; pr., distal process, f nat. size. The patella (text-fig. 29) is much like that of Uintatherium. The surface for the outer condyle (o.) of the femur is smaller than that for the inner (?.); both are gently concave from above downwards, and very nearly flat from side to side. Below the articular surface the bone is produced downwards into a blunt triangular process { 'pT.). The anterior face as usual consists of a greatly swollen and roughened mass of bone. The tibia (text-fig. 30) is a short stout bone considerably expanded towards the articulations. The facets for the condyles of the femur are deeply concave. The inner (^.) is much the larger and is oval in outline, the long axis being antero- posterior, The outer (o.) is smaller and more nearly circular, and its long axis is from within outwards : in front of it and to the outer side of the anterior TKirriAliY VEKTE15RATA OF THE FATt.Al. 52 portion of the inm'r facet the surface of the l)one slo))es strongly downwards towards tlie not v('ry ])ronunent but massive cnemial crest {cn.). Immediately beneath tlie ])ostero-external angle of the proximal end of the hone is a l)road lacet (/.) for union with the upper end of the fibula. Beneath the cnemial crest the shaft is trilu'dral ; its posterior face is nearly flat, the antero-external first concave, then towards the middle of the bone flat, the antero-internal rounded. 'ITie distal end of the bone is expanded laterally, so that it is nearly twice as wide in that direction as from before backwards. The greater portion of the distal Text-fig. 30. Right tibia of Arninoitheriinn zitteVc. A, from front ; R, from baiF ; C, jiroximal end ; 1), di.stal end. (xxt., surface for astragabus ; oi., cnemial crest ; surface for proximal (uid of fibula ; f.\ suiTace for distal end of filjula ; inner surface for femur; i.m., internal malleolus; o., outer surface for femur, f nat. size. end is occupied by the slightly concave surface for the astragalus (a, ‘if.). 'Fliis is produced somewhat downwards into a ])oint jiosteriorly and much more strongly internally, where it runs down on to the face of the blunt interuiil malleolus {i.m.). External to the astragalar surface, and se])arated from it by a slight ridge, is a roughly semicircular facet (/.') looking downwards and outwards, for union with the ('xpamh'd lower end of the fibula. The tibia is extremely like that of the Dinocerata (except that tin' femoral facets are more unequal in size), and differs from that of Klcplias in being shorter and AKSINOITHERIUM. 53 stouter, having a larger cnemial crest and a more regularly concave aslragalar surface. d'ho jihula (text-fig. 31) possesses a slender strongly-curved shaft with expanded articular ends. The n]iper end bears on its tibial face {t!) a flattened or even slightly concave facet for union with the tibia ; the outer face is swollen and roughened, and is partly divided into two by a longitudinal groove. The shaft is slender and is Text-fig. 31. Left fibula of Arsinoithenum zitteli ; A, inner (tibial) face ; B, outer face ; C, distal end. ast., surface for astragalus ; calc., surface for calcaneum ; e.7n., external malleolus ; t,, distal tibial surface ; t.', proximal tibial surface, f nat. size. compressed from before backwards, bearing on its inner face a longitudinal ridge ; it is strongly curved, the convexity being on the tibial side. The distal third of the shaft is greatly expanded and deeply concave, being closely applied to the outer side of the distal portion of the tibia. Distally this deep concavity is closed by 54 TKRTIAIIY YEliTEP/lUTA OF THE FAYCiM. a sliclf-liko i)Tojecti()ii l)cnriit^- on its iii)])cr surface a facet (t.) for articulation witli tlie tihular facet of tlie tibia, above described. Beneath this facet the distal ])ortion ()f the til)ula, forniiiif>' tlie external malleolus projects considerably, and its outer face is su'ollen and roui>li('ned, while its inner, nearly triangular surface bears Ovo facets almost in the same ])lane. Of these facets the upper (ast.) is the smaller and articnlates with the astragalus, so that when the tibia and fibula are in their iratural position with regard to one another the astragalar facets of the twm bones form a continuous concave surface. The lower and larger facet {calc.) articulates with the large fibular facet of the calcaneum, wdiich lies immediately external to the ectal facet for the astragalus. The astragalar and calcaneal facets of the fibula are only separated by a slight ridge. The fibula, ])articularly its distal portion, is extremely like that of Elcphas. In both there is the same concavity of the inner face of the distal end, the prominent facet for articulation 'with the tibia, and an almost identical arrangement of the surfaces for the astragalus and calcaneum. The fibula of Uintatherium is different in all these particidars, more especially in the very small size or oven complete absence of the calcaneal facet ; it should, howmver, be remarked that in the earlier Amblypoda, e. g. Con/phodon, the calcaneal articulation of the fibula is well developed, and this is no doubt a primitive feature. Examples of the a.'drafjahts (text-fig. 32, 2 a, 2 b, 2 c) are among the most numerous of the bones found in these deposits, and it is remarkable that of the very large number collected nearly all are of the form now described and referred to Arshwithcrium on tlie following grounds : — (1) their large size and massive structure; (2) the agreement of their articular surfaces with those of the tibia above described and with the most common form of calcaneum ; (3) the presence of articular surfaces for both cuboid and navicular excluding the possibility of this type of astragalus belonging to Fakco mastodon, of which, moreover, tlie calcaneum and probably the astragalus are known. From these considerations it will be seen that the astragalus now described may be regarded with confidence as that of Arsinoithenani. 'J'he proximal articulation for the tibia (text-fig. 32, tih.) is gently convex from before backwards, and very slightly concave from side to side. Posteriorly there is a notch (w.), but there is no perforation as in some of the Dinocerata. The articulation does not extend farther back on the inner than on tlie outer side. On the outer side is the fibular surface {fib.) looking outwards and somewhat upwards, and passing above into the tibial surface. On the inner side the main tibial surface is continuous with an inner hree looking- inwards and upwards, and snpjilying a surface for the articulation of the internal malleolar jirocess of the tibia. Beneath and behind this surface the jiostero-internal angle of the bone forms a jirominent tuberosity. 4'he surfaces for the calcaneum AKSINOITIIERIUM. 55 arc the ectal (ec.), which is the smaller and is convex from before backwards, and the snstentaciilar (sits.), which is much larger, flat anteriorly and concave behind. Text-fig. 32. Left calcaueum and astragalus of Arsinoitherium zitteli : 1 A, calcaneuin from above ; 1 b, distal surface of calcaneum ; 2 a, tibial surface of astragalus; 2 b, anterior view of astragalus; 2 c, distal surface of astragalus. cuh., facet for cuboid ; ec., ectal facet ; Jih., fibular facet ; n., notch in binder border of tibial surface ; nav., navicular facet ; sus., sustentacular facet ; ? t., facet for tibiale ; t.c., tuber calcis ; tih., surface for tibia. 2 nat. size. TI-:HTIAUr YEliTEiniATA OE THE IAVTCM. OG Those two lacots a, re so])aratc(l froin one another })osteiiorly by a narrow groove, and anteriorly l)y a dee]) Ibssa. There; is also a deep fossa lying to the inner side of the ante'rior part of the sustentacular (acet. Anteriorly this siirface joins that for the cul)oid {cuh.), making an angle of about 100° with it. 'flu; cuboid surface {cub.) is about one-third of the whole distal articulation. It is gently convex in all directions, and is sejearated from the navicular surface by a slight obliepie ridge. The navicular surface [nao.) occupies nearly all the rest of the distal face of tlie bone; it is strongly convex from side to side, and slightly so from before backwards. Internally it is continuous with a small facet (U.)’ Avhich may indicate the existemee of a distinct tibiale such as occurs in some Amblypoda. On the anterior face of the bone the lower edge of the tibial surfice is separated from the upper edge of the cuboid-navicular surface by an interval of about 2 to d cm., in which tlie surlace is concave from above downwards. This astragalus, though superticially similar to that of Elephas, differs from it fundamentally. Among the peunts of difference are : — (1) articulation with cuboid and conscapient did'erent form of the distal surface ; (2) much larger surface for fibula ; (d) presence of a large and somewhat concave surface for the internal malleolus (in the early Proboscidea this seems to have been present, see below) ; (4) wide difference in the form and projjortions of the two calcaneal facets; in Eleplias the ectal facet, in Arsinoitherium the sustentacular, is much the larger. The likeness to the astragalus of the Amblypoda is somewhat greater, particularly in the presence of both cuboid and navicular facets. But the form of the calcaneal facets is different, and the posterior notch is slightly marked, while in the Amblypoda it may even be converted into a foramen. The calcaneum (text-fig. d2, 1 a, 1 b) is a very short stout bone somewhat like tliat of the Dinoccrata. The tuber calcis (t.c.) is very short and thick, and terminates posteriorly in a great rugose mass of bone. The ventral surface is greatly swollen at the sides, but in the middle line there is a deep concavity. There are two oval, obliquely-arranged facets for articulation with the astragalus. Of these the ectal (ec.) is concave from before backwards, while the inner (sustentacular) facet (sii.s.), which is much the larger, is flat in front and convex behind, owing to tlu' deflection of its hinder portion. The two surfaces are separated posteriorly by a deep narrow cleft which, towards the front, becomes wider and dee[)er. The anterior edge of the sus- tentacular surface forms the up))er border of a small facet lying at right angles to it (Inav.), and probably indicating that tlu're was a small articulation with tlie navicular. 'I'he cuboid facet (cub.) is small and oval, its upper inner angle being continuous with the small navicular facet just desci-ibed. Beneath the navicular and cuboid articulations is a valley bounded below by a rugose and swollen border. 'I'lie fibular facet (Jib.) is large ; it looks outwards and upwards, and is convex from before backwards, while its ujiper border meets the ectal facet in a sharp AKSINOITHEKIUM. 57 angle. When the astragalus and calcaneum are articulated their fibular facets form an almost continuous convex surface. The calcaneum differs from that of Elephas in (1) its much shorter and stouter form, (2) the much smaller size of the cuboid surface, (3) in having the sustentacular facet for the astragalus larger than the ectal. Probably the foot approached the ])lantigradc condition more nearly than is the case in Elephas. The calcaneum in the Dinocerata is somewhat more similar, but has the astragalar facets more nearly equal in size and convex, and the sustentacular portion of the bone is more prominent. The navicular (text-fig. 33) is of great width and at the same time is very short. Its proximal surface {ast.) for the astragalus is gently concave. The distal surface is divided into three facets ; of these the inner {c. 1) is slightly convex and extends nearly to the hinder border of the bone ; the middle (c. 2) is depressed, slightly Text-fig. 33. Left navicular of Arsinoitherium zitteli: A, from front; B, from above; C, from below. ast., facet for astragalus ; c. 1, c. 2, c. 3, surfaces for the cuneiforms ; cud., facets for cuboid. | nat. size. concave from side to side, and is limited posteriorly by a deep pit ; the outer (c. 3) projects considerably below the others, so that this region of the bone is much deeper than the rest, with the surface roughly triangular in outline. These three facets must have articulated with the three cuneiforms, none of which are known ; the ectocuneiform must have been a very small element. The outer (cuboid) face of the bone bears along its upper edge a well-marked facet for the cuboid [cuh.), and there seems to have been a less distinct facet for the same bone on the lower border. I 58 TERTIAET VERTEBRATA OE THE EAYtM. 'I'liis bone differs widely from the navicular of Eleplias in articulating with the cuboid by its outer face only, and not being interposed between that bone and the astragalus. From the navicular of the Amblypoda it differs mainly in the depth and ])rominence of the ectocuneiform region, which is such that the outer face of the navicular articulates with the cuboid by both its upper and lower edge. In Uintatherium and Corypliodon the navicular articulates with the upper edge of the cuboid only and the lower portion of the inner side of that bone joins the ectocuneiform. It may be suggested that it is just possible that in the bone here described and figured the ectocuneiform may be fused with the navicular, but there is no actual trace of such a fusion having taken place in any specimen examined. Text-fig. 34. B. X I Right cuboid of Arslnoitherium zitteli : A, navicular face ; B, from above ; C, from below. ast., facet for astragalus ; calc., facet for calcaneum ; mt., mt. 4, mt. 5, facets for the metatarsals ; nav., facets for navicular. | nat. size. The form of the bone which is regarded as the cuhoid of this animal is shown in text-fig. 34. The proximal surface (ast.), which articulates with the outer third of the distal end of the astragalus, is nearly flat and almost circular in outline, only the navicular border being somewhat flattened. Connected with the postcro-extcrnal angle of the astragalar surface is a small facet (calc.), looking backwards, outwards, and upwards, for articulation with the calcaneum. The inner face of the bone bears two small facets (nav.) for union with the navicular, one on the upper border, the other on the lower, the two being separated by a deep groove. The distal surface* is gently convex ; in front it is slightly bilobate {mt. 4, mt. 5) and clearly articulated with two metatarsals ; and the postcro-internal angle is produced into a blunt tuberosity. AKSINOITIIEEIUM. 59 This bone is entirely nnlike the Proboscidean cuboid. It is more like the cuboid of Umtatherium, but differs from that in several respects — e. g. in the much smaller size of the calcaneal hicct. The metatarsals arc not definitely known, but the collections include a number of short and very massive metapodials which probably belong to the hind foot of this animal. Two of those are shown in text-fig. 35 Of these one (2 a, 2 c) probably belongs to a middle digit. Its proximal articulation (2 a) is gently convex from before backwards, but does not extend quite to the hinder surface of the bone, which is produced posteriorly into a large tuberosity. In front the proximal articulation is Metatarsals of ArsinoitJierium zitteli : 1 A, proximal end of lateral metatarsal ; 1 B, same specimen from front ; 2 a, proximal end of middle metatarsal ; 2 c, same specimen from front. mt., facet for adjacent metatarsal, g nat. size. produced considerably to one side, probably the post- axial, and bears a facet for articulation with the next metatarsal (mt.). The shaft of the bone is slightly contracted. The distal articulation is wide and consists of two surfaces, both convex from above downwards and concave from side to side and meeting at an angle on the distal end of the bone. The anterior and larger of these surfaces articulated with the first phalange and is limited above by a groove, above which is a strong rugose ridge extending across the whole face of the bone and produced laterally into tuberosities. The smaller posterior surface no doubt supported a sesamoid or a pair of sesamoids. Text-fig. 36. r Jlestored skeleton o£ Arsinoithcrium zitteli. Th*.' imsbadod portions are not represented in the collections, nat. size. ARSINOITUERIUM. (51 The other specimen (1a, 1b) seems to bo a lateral metatarsal. It is shorter and stonter than the last, and is distinctly convex towards the median axis of the foot. Its proximal surface is convex from before backwards and slightly concave from side to side. Posteriorly it is produced backwards into a pair of blunt tuberosities. The outer face is occupied by swollen roughened ridges. The distal articulation is similar to that described on the other metatarsal, except that the posterior surface is distinctly bilobate and no doubt bore a pair of sesamoids. Th.e phalanges are unknown. Text-fig. 37. The first and second metacarpals and the phalanges are restored, nat. size. From the large mass of material in London and Cairo it has been possible to attempt a restoration of the entire skeleton, and the result is shown in text-fig. 36. The chief parts of the skeleton remaining incompletely known are the sternum, ribs, posterior caudals, and the phalanges : these are distinguished in the figure by being left without shading. With these exceptions it is probable that the figure gives a fairly accurate idea of the general form and proportions of the whole skeleton (■>2 TEliTIAKY YEliTEBEATA OF TJIE FAY^M. of Arsinoitherrimi, lhoi]<^li in tlie absence of associated scries there may l)e some doubt about the exact ))ro|)ortions of the limb-bones. Text-fig. 37 is a view of the |)elvis and liind limb seen from the front, and shows the great width of the pelvis, the ])ro])ortions of the femur and tibia, and the structure of the tarsus. Both the figures are al)ont one-sixteenth natural size, the animal having stood about T7G metres (about 5 ft. 9 in.) at the withers and measured about 2‘96 metres (9 ft. 9 in.) from the snout to rump. The determination of the systematic position of the Barypoda is rendered specially difficult from the circumstance that Arsmoitherium, the only member of the group at present known, is a highly specialised terminal form of a series of which the earlier terms are still undiscovered. Nevertheless some attempt may be made to refer this animal to its place in the system, for although in many respects so specialised, in others it retains primitive characters, and even where the degree of specialisation is great, as in the case of the teeth, it may still be possible to arrive at a fairly clear idea of the conditions that must have existed in the earlier types. From the account of the skeleton given above it will be seen that there is no doubt that the Barypoda form a subdivision of the Ungulata, belonging to that section of the order including the Elephants, Hyracoids, and Amblypoda, to which the collective name Subungulates is sometimes applied. To determine the relations of the Barypoda with the other Ungulates comparison must be made with (1) the Ih’oboscidea, (2) the Amblypoda, (3) the Flyracoidea, and (4) some of the South- American Ungulates. The last of these comparisons is necessary because Ameghino has suggested that the Ethiojnan and S. -American regions were closely connected in the later Cretaceous and early Tertiary times, and he considers that many of the main groups of Ungulates {e. g. the Hyracoids and Proboscidea) originated in S. America and subsequently migrated into Africa. It is not jiossible or desirable to discuss these questions fully here, but some allusion must be made to them. Comparison of Arsinoitherium with the Proboscidea shows that in the structnre of the skull, in the form of the molars, and in the persistence of the complete series of teeth without diastemata it differs entirely from any member of that suborder. In the skeleton, on the other hand, there are some similarities, but these seem to be merely parallel modifications due to great size and weight in the two groups, while, (»4i the other hand, differences of such fundamental importance exist {e. g. in the structure of the tarsus) that any possibility of close relationship may be excluded. Comparison with the Amblypoda shows that many points of resemblance in the skeleton exist, but, as in the case of the Proboscidea, these are probably nearly all the results of parallel evolution and are modifications dc])cndiug mainly on increasing bulk and weight. On the other hand, the great similarity of the structure of the ti’.rsus in the two cases cannot be so explained, but is ])robably a primitive character derived from similar Condylarthrous ancestors in the two cases. In the skull the AKSJNOITIIEIilUM. G3 presence of horns in the two suborders does not seem to be a character of much importance, for they differ both in situation and character and, moreover, are found in many other groups. On the otlier liand, the skulls differ widely in the form of the occipital surface, the arrangement of the external auditory meatus, the form of the premaxillae and of the anterior palatine foramina. The mandible is very unlike in the two groups, particularly in the form of the angular region. In the dentition of the Amblypoda the following im]iortant differences may be noticed : — (1) the upper incisors are small and weak and the canines large and tusk-like; (2) there is a diastema behind the canine in both jaws; (3) the cheek- teeth are relatively small and are brachyodont ; (4) in wear the upper teeth tend to give V-shaped surfaces. In a former paper (Geol. Mag. [5] vol. i. 1904, p. 158) the present writer suggested that possibly the hypsodont molars of Arsinoitherium might have been derived from some form of Amblypod tooth, but further consideration has shown that this is almost impossible. Moreover, the great differences above referred to show that the two groups are very widely separated. Comparison with the Hyracoidea is very difficult on account of the small size of the modern representatives of the group and our complete ignorance of the skeleton of the large extinct forms. In the early Hyracoidea there is a tendency for the anterior teeth (incisors, canine, and premolars) to form a continuous series, the anterior pair of incisors being more or less enlarged and separated from one another in the middle line by a short interval, as in Arsinoitherium. The molars are brachyodont, but their pattern is such that if there were an increase in height accompanied by an increasing infolding of the outer wall, they might give rise to a type of tooth very similar to the molars of Arsinoitherium, as was explained above. Since, however, these early brachyodont Hyraces are contemporaries of Arsinoitherium, it is not suggested that they are closely related ; but the circumstance that they both seem to have originated in the same region lends some probability to the belief that they may have had a common ancestry in the late Secondary or earliest Tertiary period. Dr. Ameghino has suggested in a letter that Arsinoitherium may be related to the Toxodoutia, but in spite of some superficial resemblances such a relationship does not seem at all probable. We may mention only two of the many important differences between the two types : (1) the structure of the molars seems to be totally dissimilar, and it is very difficult to see how the two types can be connected with one another ; (2) the structure of the tarsus is very different in the two cases, that of the Toxodontia apparently showing the cuboid in articulation exclusively with the calcaneum. It is to be hoped that remains of earlier members of the Barypoda may be found in the Lower Eocene beds of Egypt, and that by these the question of the affinities of the group may be definitely settled. 61 TERTIARY VERTEBRATA OF THE FATtM. Arsinoitherium zitteli, Beadnell. [Frontispiece ; Plates I.-V. ; text-figs. 1-37.] 11)02. Arsinoitherium zitteli, H. J. L. Beadnell, op. cit. pis. i.-v. 1903. ,, „ fig.s. of skull, Geol. Mag. [4] vol. x. pis. xxiii., xxiv. 1904. „ „ (J. W. Andrews, Geol. Mag. [5] vol. i. p. 157. Type Specimen. — Skull, three-parts grown, probably of male (PI. III. figs. 1, 1 a) ; Geological Museum, Cairo. The type species, with mandible attaining a length of about 55 cm. ; the length of the three upper posterior premolars and the molars together about 25‘5 cm. This is a species of very variable proportions, known by several skulls and numerous other parts of the skeleton, nearly all found isolated. Its remains are only distinguishable from those of the larger species, A. andrewsi, by their size, and it is possible that some of the specimens catalogued here {e.g. the pelvis no. C. 8413) may really belong to the latter form. Among the adult skulls there are two types distinguished by the form of the great nasal horns, namely, (i) those in which the horns are very large, trihedral, and sharply pointed, probably referable to males (PI. I.) ; and (ii) those in which the horns are much shorter, somewhat rounded, and irregularly ossified at their tips, probably referable to females (Beadnell, op. cit. pis. iii., V.). Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north and north-west of Birket-el-Qurun. C. 8130 *. Skull of a three-parts-grown animal : the type specimen figured by Beadnell in ‘ A Preliminary Note on Arsinoithei'ium zitteli, Beadn., from the Upper Eocene Strata of Egypt,’ pis. i., ii., vi. (Cairo, 1902) ; also on PI. III. figs. 1, 1 A. The dimensions are given on pp. 09, 70. The age of the animal is indicated by (1) the rounded horn-tips, (2) absence o£ prenasal bar, (3) anterior lobe of m. 3 only just coming into wear. M. 8463^'. Skull and mandible together with a rib of an adult animal, probably a male. The skull is figured in the Geol. Mag. [4] vol. x. pis. xxiii., .xxiv., also on Pis. 1., II., with the ends of the horns and part of the right side of the skull restored in plaster, the restored portions being indicated by dotted lines : i. 1, i. 3, c., and pm. 1 are wanting on both sides; the last molar is moderately worn. The mandible is figured on PI. JV. figs. 1, 1a, and was found in actual contact with the skull : i. 1, i. 3, and jnn. 1 are wanting on the left side, i. 1, i. 2, i. 3, c., and pm. 1 on the right. The dimensions of this skull and mandible are given on pp. (19, 70. J^resented hj IP. K. de Winton, Es<]., 1903. * The numbers with C prefixed are those of specimens in the Geological Museum, Cairo ; numbers v\ ith any other letter indicate that the specimen is in the British Museum. AESlNOITIIElilUM ZITTELI. 65 C. 8128. Skull of an adult animal, probably a male, very similar to last, but with horns and most of rest of skull complete ; teeth anterior to pm. 2 wanting. On the whole this is the most nearly complete skull at present known. The dimensions are given on pp. 69-70. Figured in Frontispiece. M. 8407. Posterior portion of an adult skull wanting whole of left side in front of occipital region ; the right side is well preserved as far forwards as the base of the large horn. C. 9353. Upper portion of a skull in which the anterior horns curve away from one another at a wider angle than usual, and have more sharply angulate upper inner borders. The distance between the horn-tips is 42 cm. Other dimensions of this skull are : width above auditory meatus 31’3 cm. ; length from condyles to tips of horns 80 cm. ; width of skull-roof 10’4 cm. M. 8379. Anterior portion of an adult skull, probably of a female. Figured by Beadnell, op. cit. pis. iii., iv., V. The horns are much smaller and straighter than in M. 8463 or C. 8128, and are irregularly ossified at the summit. The last molar is well worn and the prenasal bar fully ossified. Of the teeth, i. 1, i. 2, i. 3, c., pm. 1, and pm. 2 are wanting on the left side ; on the right pm. 3 also is missing. The height from the tip of the snout to the summit of the horns is 55 ora. ; length of molar series, 19 ’5 cm. ; length of pm. 3-4 together, 6‘5 cm. The whole of the skull behind a vertical plane passing in front of the right frontal horn and behind the left is wanting. Presented hy the Egyptian Government, 1903. C. 8256. Portion of the nasals forming posterior side of horn at fork. This specimen shows the median longitudinal buttress and the smaller transversely arranged ridges running at rio'ht anodes to it. O O M. 8830. A similar specimen to the last. Presented hy the Egyptian Government, 1904. C. 8794. Posterior portion of skull. From the cranial cavity of this specimen the cast numbered M. 9087 was made. C. 7805. Skull of a young individual, figured on PI. III. figs. 2, 2 a, 2 b. Most of the sutures remain open and are shown in the figures. The ends of the front horns are rounded, the prenasal bar is uuossified, the posterior molar is uncut, and the much-worn molariform last milk-molar is still in place. This tooth is 4‘9 cm. long (outside measure) ; m. 1 is 5'5 cm. long : the germ of the last molar is still quite imperfect. Dimensions given on pp. 69-70. 51. 8800. Skull of a young individual somewhat smaller, but at the same time older than last (C. 7805). On the left side, the zygomatic arch, the maxilla, and the teeth have been restored, likewise the tip of the left nasal horn. The last milk-molar seems to have been replaced, and the last molar, though in a much more advanced condition than in C. 7805, was still uncut. The prenasal bar is absent. The sutures are obscure, owing to the condition of preservation. Dimensions given on pp. 69-70. Presented hy the Egyptian Government, 1904. il. 8470. Numerous portions of a young skull associated with a portion of a mandible with m. 1 and m. 2 and some well-preserved upper and lower teeth. Of these an upper incisor is figured on PI. V. figs. 1, 1 A ; an anterior left upper pm. {‘ipm.2), figs. 3, 3a ; a right upper pm. (? pm. 3), fig. 2 ; a left upper m. 3, figs. 6, 6 A, 6 B ; also a left lower E 06 TI':RTIAKY VEliTEiniATA OE THE EATOM. molar, (jo's. 4, 4 a. With tluwe th(‘re wore also associated the distal epiphysis of a left • ulna, the distal half of a ri^ht radius, a left scaphoid, a left unciform, a left fourth UK'tacarpal, and a ri^ht maonum. Presented hj IE. E. de Winton, Esq., Ih03. M. 8475. Upp(U- portion of shull of very young animal showing ])arieto-frontal suture and anterior border of the frontals. This specimen also shows that the great frontal sinus is continued into the frontal (posterior) horn. There is no trace of the occipito-parietal or int('r-[)arietal sutures. Presented hj TE. E. de Wlnton, Esq., 1*103. M. 8462 a. Right maxilla with the molars and last two premolars preserved : m. 3 is well worn, the animal being old. The base of the zygomatic process is preserved ; the antorbital foramen is smaller than in most specimens. The length of the molars is 18'2 cm., that of the two ])remolars 7'5 cm. This maxilla may belong to the same individual as the mandible M. 8462 h. Presented hj W. E. de Winton, Esq., l'J03. C. 7843. Palate and cheek-teeth of a young individual in which pm. 4 is just being cut andynn.d is slightly worn ; m. 3 and one of the anterior incisors of the right side are just appearing. The base of the zygomatic process and the antorbital foramen are preserved. G, 7912. Left maxilla of a young individual in which p?u.4 and the hinder column of m. 2 are slightly worn. The length of m. 1 and m. 2 together is 10'2 cm. ; length of qnn. 2~qim. 4, 8’4 cm. C. 7844. Right maxilla with pu;. 2-/u?u 4 ami m. 1-?>k 3. Last molar just cut, but not in wear. Length of m. 1-m. 2 is 1()’2 cm. ; length of pm. 2-pm. 4 is 8'4 cm. C. 8253. Left maxilla rather older than the last, m. 2 being more worn. Tiie posterior column of m. 3 is missing. The length of m. 1-m. 2 is 1E6 cm. ; length of pm. 2-pm. 4 is 8’6 cm. M. 8801. Portion of left maxilla with the molars and pm.-i in situ. The posterior column of ?n. 3 not yet in wear. Length of molar series about 15'5 cm. Presented hp the Eijipptian Gooernment, 1904. M. 8802. Portion of right maxilla with ?/;. 2 and ni. 3, the ])osterior lobe of the latter just coming into wear. Presented h>/ the Epp/>tian Government, 1904. JI. 8472. Portion of left maxilla and anterior end of jugal ; the antorbital foramen is preserved. One tooth, probably the last milk-molar, is in situ ; above and a little in front of this is the fossa, in which lay the germ of qnn. 4 or q^m. 3. The milk-molar is entirely molariform ; the length of the inner side of the crown is 4‘2 cm. Presented hp II'. /f. de Winton, P.nq., 1903. M. 8471. Portion of left maxilla with three teeth in situ, probably ))im. 2, mm. 3, and mm. 4 ; mm. 1 and a milk-incisor are also preserved. J\Im. 4 is much less worn than in the last specimen ; both it and m/u.3 are molariform. Min. 2 consists of an outer wall, two transverse crests, and a well-developed cingulum on the antero-intei nal border ; mm. 1 consists of an outer wall conn)osed of two elements and united anteriorly by a slight transverse crest with the strongly developed cingulum. The incisor is a small, cylindrical, slightly spatulate tooth without a cingulum. The lengths of the milk-molars are: — rnrn. 1, 1'9 cm.; mm. 2, 2'3 cm. ; mm.?), 3’3 cm.; mm.i, 4’f cm. Eigiireil on PI. V. tig. 5, 5 a, and text-tigs. 7. Presented bp IE. E. de Winton, PJsq., 1903. i\RSlNOrn[EllTUM ZITTELT. 67 C. 8252. C. 9436. M. 8826. M. 8474. M. 8539. M. 8540. M. 9087. C. 8802. C. 8129. M. 8408. Portion of riglit maxilla with the four milk-molars in situ. This specimen is slightly larger than the last, hnt otherwise closely similar. Portion of right maxilla similar in age to the last, whth min. 2 and mm. 3 in situ. Portion of left maxilla somewhat younger than M. 8472, with ?n?n. 4 and mm..‘?> in .situ, and the parts of the germ of the premolar replacing the latter. If this interpretation he correct, the height of the crown of mm. 4 is very remarkable, the hypsodont condition being quite as pronounced as in the permanent molars. Thus the width of the posterior column of mm. 4, which is already somewhat worn, is about 3 cm., its height in a straight line 7'7 cm. Presented hy the Egyptian Government , 1904. Left premaxilla of young individual showing the germs of i. 1 and i. 2. Presented hy W. E. de ^]dnton, Esm. 1 is just appearing. This tooth is placed very obliquely in the jaw, and must gradually rotate into its normal position as the growth of the mandible allows it room to do so. Presented hy the Egyptian Government, 1904. M. 8823. Anterior portion of right ramus of very young individual similar to M. 8822. In this also the crown pm. 1 is just appearing, and is here placed almost transversely. In front of it are the alveoli of the canine and three incisors. Behind is the broken base of mm. 2. The symphysis extended back as far as the posterior end of mm. 2, and the mental foramen is beneath the anterior column of the same tooth. Presented hy the Egyptian Government, 1904. HI. 8410. Left upper molars. M. 8825. Nearly unworn upper m. 3. Presented hy the Egyptian Government, 1904. C. 8942. Upper m. 3 slightly worn. C. 8943. Upper m. 2 with inner wall just formed, showing the roots. M. 8382. Eight upper molar, much worn, showing roots. Presented hy the Egyptian Government, 1902. M. 8804 a. Right upper molar, much worn, showing roots. Figured on PI. V. figs. 8, 8 a. Presented hy the Egyptian Government, 1904. M. 8804. Right upper molar, rather less worn than last. Figured on PL V. fig. 7. This specimen and the last are very large, and may belong to Arsinoitherium andrewsi. Presented hy the Egyptian Government, 1904. C. 9236. Two well-preserved right upper molars. C. 8291. Two upper molars considerably smaller than usual, possibly indicating the existence of a smaller species. C. 7921. Right upper premolar. Dimensions (in centimetres) of skulls of Arsinoitherium zitteli : — 1. 2. 3 (typo). 4. 5. C. 8128. M. 8463. C. 8130. C. 7805. M. 8800. Length from condyles to tip of snout 80 77 74 . • . . 65-5 „ » ,, born 109-4 100 78-4 73-4 64 „ „ „ small horn . . . 42 38 38-9 36 32-7 Width of roof at narrowest (between temporal fossae) 11-4 13 9-7 10-4 12 „ at zygomatic arch 35-6 33-5 31-6 28-3 31 app. Greatest width of occipital surface 25-7 app. 26 app. 24-6 21 20 „ „ between tips of small horns . . . „ „ of the combined bases of the large 25-4 app. 24-5 23-2 17-1 17 app, horns „ „ of each horn at base (antero- 24-5 27 24-6 21 16-8 posterior) 18 22 15-2 14 app. 13-4 70 I'J^KTIAJiY YEETEJ5RATA OF THE EAYt’M. J )iiii(‘iisions [coiitiinu'd) : — ■ 1. 2. 8 (type). 4. 5. c. 8128. M 8463. C. 8130. C. 7805. M. 8800. (Jroivlc.sf widdi of oacli liorti at base (side to side) . IG 14-5 11-5 10-3 8-2 „ „ above auditory opening .... 35 33 31 28 27 app. Ijengtli from basion to posterior border of palate . 36-9 3G 34 31-4 30 „ ,, tip of snout 74 70 G8-5 9 G1 Ijengtb from boi’der of j)alate to tij) of snout . . 38-5 35 35-3 9 33 Height from tip of snout to end of large borns . . 78 72 59 9 39 „ angle of pterygoids to roof of skull b(‘t\veen small horns 3S'5 app. 34 32'7 app 30-5 25-5 Wddth between outer angles of condyles .... 23-9 24 21 app. 20- G 16 „ of foi'amen magnum 7 10 8 7-5 6-6 Height of foramen magnum 4-5 5*5 5'5 4-7 4-6 Histance between tips of large horns 32 37 25 18-5 (restored). 19-5 app. Length from fork to tip of large horns 39 40-5 21 15-G 13-0 „ upper edge of nasal opening to tips of lai'ge borns GO 53 35-7 2G-2 19-4 The dimensions (in centimetres) of the teeth in t liese skulls are D. 8128. M. 8463. C. 8130 (type). C. 7805. M. 8800. Length of molar series (outside of crown) . . . lG-8 16-5 lG-7 „ 4 „ „ ... 8-G 9-3 8-6 8-7 ., ])m. 2-m. 3 ,, ,, ... 25-4 25-7 25-5 . „ ■„ (basal length) 28 28-5 9 ,, m. 3 in mid-line 4-h 4-4 9 uncut. ,, m. 2 6-7 5-8 4 + G‘5 5-4 ,. «!. 1 5-2 5-3 5-2 5-2 5-5 ., 2"”- d 3-1 3 2 mm. 4, 4‘9 3-2 2-5 2-8 2-8 l>n<- - 2-4 2-6 2G 2-6 The dimensions (in centimetres) of the mandibles mounted with C. 8128 and M. 84G3 respectively arc : — C. 8129. M. 84G3 (assoc'i.'vted). Total length 55‘5 52-5 Height at coronoid 3G'5 31-5 AVidth of condyles 1 1 -0 10-2 „ ascending ramus .... 21-7 17 Depth of ramus at m. 3 9-3 8-2 Total width between posterior angles . 29-5 Length of symphysis 18 AVidth between upper ends of coronoid processes . 17-5 Antero-posterior length of crown of m. 3 . . . 5-5 5-2 „ 1, „ «*• - (>*.> G-2 )) 11 51 * f 5-5 5 „ „ „ 1 . . . 3-9 3 „ „ „ 1 . . . 3-2 2-8 55 )5 15 <■> . • 2-7 2-G ARSINOITIIEREUM ZITTELT. 71 C. 8060. Atlas vertobni associatt'd with tlio type skull. Tn this specimen the lateral surfaces for the axis are roughly triangular, their inner sides hounding the hroad notch for the odontoid being straight and nearly vertical. Condylar cups hroad and deeply concave, extending up to the level'of the neural arch and down to the ventral bar. M. 8387. Atlas. Presented hjj the dhjyptian Government, 1902. C. 8064, C. 8262, C. 8973, C. 9087. Four specimens of the atlas. C. 8077. Atlas with incomplete transverse processes. M. 8816. Atlas with right transverse process imperfect. Figured, with process restored, text-fig. 8. Presented hy the Ecjyptian Government, 1904. M. 8460, M. 8494. Two specimens of the atlas. Presented by IF. E. de Winton, Esq., 1903. M. 8816 a. Atlas of small individual. Lateral facets for axis more quadrate than usual. Presented hy the Erjyftmn Government, 1904. The dimensions (in centimetres) of some of the above specimens are given in the following table : — C. 8060. M. 8387. C. 8262. C. 8077. M.8816. C. 9087. AVidth at transverse processes . 31 + 43-6 47-4 42 39 -.5 ,, condylar cups . 23 24 app. 20-2 19 21-5 23-7 „ surfaces for axis . 18-7 19 17 16 16-5 18-3 Extreme height 15'8 18 lo-7 12-6 16-7 1.5-8 Antero-posterior width of transverse processes 5-8 8 8'5 5-2 7-3 7-7 Length of neural arch 6-5 8-4 7-7 5 6-1 8-3 C. 7888. Large and nearly perfect axis. The odontoid is very short and stout. Transverse process perforated by large vertehrarterial canal ; paired hypapophysial tuberosities on postero- ventral border of centrum. M. 8815. Axis, large specimen with broken transverse process. Presented hy the Egyptian Government, 1904. M. 8388. Axis, rather smaller than last. Presented hy the Egyptian Government, 1902. M. 8839. Axis of small individual. Presented hy the Egyptian Government, 1904. M. 8411. Axis wanting transverse processes. Figured in text-fig. 9. Presented hy W. E. de Winton, Esq., 1903. C. 7810, C. 8086, C. 8990. Three specimens of the axis. C. 8072. Axis, a small specimen with a relatively smaller and less massive odontoid process. The dimensions (in centimetres) of some of the above axes are given in the following table : — C. 7888. C. 7810. C. 8086. M. 8815. M. 8388. M. 8411 Height to summit of arch , . . . 21-3 18-5 181 18 17-5 17-3 AVidth of anterior end 19-9 19-5 18 17 17-5 „ of posterior end 14-5 13-1 13 13 13-5 „ at transverse processes . . . . ... 32 26 Length (along ventral surface to tip of odontoid process) ... 15 14-8 14-1 15-5 14-8 13-7 In addition to the atlas and axis numbered C. 80G4 and C. 7888, the following series of vertebra; 72 TEllTIAET VERTEJ3EATA OF THE FAYOM. lias been selected I'roni the collection at Cairo as forming an approximately complete vertebral column. Owing, liowcA cr, to the great variation in size in individuals of the present species it was impossible to make a very satisfactory set, and it is not even certain that some of the smaller vertebrae may not belong to Paltvotnafilodon. Only the discovery of an associated series can make it jiossible to settle detinitely the structure of the vertebral colnmn and the number of vertebrae composing its different regions. The description given above (pp. 27-32) is founded on this series, and the figures also are, for the most part, taken from vertebrae composing it. The numbers of the vc'rtebrae behind the cervical region are only approximate. C. 8303. Third cervical vertebra (text-fig. 10, A). C. 9097. Fourth cervical vertebra. C. 8294. Fifth cervical vertebra (text-fig. 10, B). C. 9083. Sixth cervical vertebra. C. 9082. Seventh cervical vertebra (text-fig. 10, E). No vertebrarterial canal. Rib-facets on hinder face at ventral outer angle of centrum. The dimemsions (in centimetres) of these cervicals are given in the following table : — C. 8303. C. 9097. C. 8294. C. 9083. 0 9082. Greatest width of ceutrum . . . . . . . 13-6 14-5 13 13 135 „ height „ ... ... 11 11 11-3 11 11 Length of centrum (in middle) . . ... 3-3 4-7 4-7 6 5 Height to top of arch ... 18 17-1 17-5 . . 18-7 Width at transverse processes ... 29 21-5 23-5 Heiglit of neural canal . . . . 4 4 4-3 5 C. 9089. Anterior thoracic vertebra. Sjune higher than in last cervical. C. 8270. Anterior thoracic vertebra. At this point there is probablj' a gap in the series. C. 7806. Thoracic vertebra (text-fig. 11). S})ine very high, broad. C. 8316. Thoracic vertebra belonging to a smaller individual than the last. C. 9215. Thoracic vertebra of a small individual. Neural spine shorter than in last. C. 9091. Thoracic vertebra (text-fig. 12). Centrum is somewhat narrowed ventrally. Broad, flattened, transverse processes, with oval flat rib-facets (t./.) towards the front of their outer ends. Neural spine (n.sji.) strongly inclined backwards, upper end slightly bifid. The dimensions (in centimetres) of the last six verfebiae are given in the following table: — Height of centrum .... AVidtli „ .... Length (on ventral side) . . Height to top of neural spine Width at transverse processes Behind C. 9091 there seems to be vertebra is shown in text-fig. 13. C. 9089. C. 8270. C. 7800. C.831G. 0 921. '3. C. 9091. JO 10-2 10-5 8-2 8'2 7'7 13-7 13-5 12-5 11 10 1()'3 0-5 7-4 6-8 6 6-5 22 -p 27 24 26-2 19-7 24 26-7 26 25-6 gap in the series, in which the neural spines shortened, the , and the zygapophy ses bccanu cylindroid. This type of AliS FN OlTIl ERLUM Z I TTEL 1. 73 C. 8096. Thoracic vertebra (toxt-fi^. 13). C. 8097j C. 9085. ? Thoracic vertebrae. C. 7886, C. 8277, C. 8286, C. 9077, C. 9106. Thoracic vertebrae. C. 9228. Thoracic verh^bra (? last). The dimensions (in centimetres) of the thoracic vertebrae enumerated above are : — C. 8096. C.8286. C.9077. C. 8277. C. 8097. 0.9085. 0. 7886. 0. 922S. AVidtli of anterior face of centrum . 11 10-8 11-4 10 11 10 11 11-G lleiglit 6-G 6-7 G-4 7-5 9 8 7‘7 7-4 Length of ventral border of centrum . 7 8-0 7'7 7-2 ? 8-3 8-2 7 7 Height to top of neural arch . . . 17-4 18-2 16-1 ? ? 18-2 18 18-2 18'2 C. 8776, C. 9036, C. 9100. Lumbar vertebrae. C . 9220. ? Sacral vertebra. C. 9092. ? Anterior .sacral vertebra (text-tig. 14). C. 9093. Second sacral vertebra. The dimensions (in centimetres) of these lumbar and sacral vertebrae are : — 0.9100. 0.8776. 0. 9036. 0. 9220. 0.9092. 0. 9093. AVidth of anterior face of centrum . . 12-4 11 12-7 11-3 12-2 11-4 Height „ ,, . . / '5 7-5 6-7 G G-7 5-2 A’entral length of centrum 7‘8 8-8 8 7T 7'5 8-4 Height to top of neural arch .... 20 . • 13-5 13-4 13 app. 10 AVidth at transverse processes .... 23’6 25-5 30 app. 3G 35 36 C. 7881. Anterior caudal vertebra. C. 7887. Caudal vertebra. C. 9109. Posterior caudal vertebra. The dimensions (in centimetres) of these caudal vertebrae are : — 0. 7881. 0. 7887. 0. 9109. AVidth of front of centrum .... 6-3 4? 3-3 Height „ „ .... 3-5 3? O o Height to top of neural arch .... . 5 . , AVidth at transverse processes . . . . IG-p G Length of centrum 6-2 5-5 4-3 Cither vertebrae in the Cairo Museum are : — C. 8309. Cervical vertebra, probably the third. Width of centrum 12'5 cm., length 4'9 cm. C. 7811. Cervical vertebra, probably the fourth. AVidth of centrum 11’3 cm., length 4‘t! cm. C. 8302. Cervical vertebra, probably the fifth. AVidth of centrum ll'fi cm., length 4 cm. These three vertebrae, C. 8309, C. 7811, and C. 8302, have been })laced with the atlas and ax i.< numbered C. 8990 and C. 8973 respectively. L 7-J Tl'in'IAIJY VJ'Jrrj'liHATA (')F TJIE FAA'UM. In .'uldition lo ilio atliiscs and ax(‘s above einnnorated, the following vertebrae are in the British AI usenni : — M. 8840. Three* speciinens of a cervical vertebra, probably the third. Presented Inj the Kcjyptian Government, 1904. M. 8817. ('crvical vertebra, jirobably the fourth (text-fig. 10, C, D). Presented Inj the Pjjyptian Government, 1904. M. 8495. Cervical verfe'bra, probably tlie fifth. Wanting part of the neural arch and the trans\(‘rse proee.s.s on one side. I’resented hy I'C. K. de Winton, Esq., 1903. M. 8495 a. 1 m perfect eer\ ieal vertebra. Presented hy W. E. de Winton, Esq., 1903. M. 8389. liust cervical vert(‘bra, wanting neural arch. Presented hy the Eyyptian ( rover nment, 1902. M. 8841. Anterior thoracic vertebra. Presented hy the Eyyptian Government, 1902. M. 8841 a. Anterior thoracic vertebra, wanting neural spine. Presented hy the PJyyptian Government, 1902. M. 8496. Thoracic vertebra, posterior to last. Neural spine iiuj)erfecf. J 'resented hy IT. PJ. de ]Vinton, Esq., 190i). M. 8841b. Thoracic verteln-a, posterior to last. Neural spine imperfect. Presented hy the P]yyq>tian Government, 1904. M. 6841c. Imperfect thoracic \ertebra, posterior to the last. Presented hy the Eyyj>tian Gove)‘nment, l'.H)4. M. 88 lid. Thoi ■acic vertebra, posterior to the last. M. 8818. Thoracic vertelira, jiosterior to the last. Presented hy the PPjyjdiati Government , 1904. J’resented hy the liyyqtlian Government, 1904. C. 8433. Nearly perfect left scapula (text-fig. 1')). M. 8874. riaster cast of the last specimen. C. 8434. Left scapula. M. 8469. Left scapula, wanting antero-superior portion Made in the Eritish Museum. M. 8391. Glenoid })ortion of scapula. The dimensions (in centimetres) of these specimens are given below: — Presented hy IT. IC.de Winton, JCsq., l'.>03. I’ resented hy the Eyyptian Government, 1902. .Length of suprascapular border C. 84;i3. 50-2 C. 8431. r)4-;j M.84(;i). M. 8391 ., from antero-superior angle to end of coracoid p)rocess 40-7 44-3 a|)p. „ from posterior angle to glenoid cavity . . OO 157 37 Height of spine 11-5 1 1-.3 Ja-ngth of glenoid cavity 14-4 lo k; 14-2 AVidtli of glenoid cavity S 9-2 ap]). •) V ■ /' neck of scapula 2(1-2 2()-4 2(.)-5 l!)-o AiisiNoiTJi zitteli. C. 8150, C. 8155, C. 8855, C. 9243. Piiolit luinu'ri. M. 8819, M. 8820. Left humeri. Presevied htj the Jhjj/ptian (jlovemment, M. 8392 a, M. 8392 b. L('ffc humeri. Preheated hj/ the I'hji/pfiaa (Government, 1902. C. 8159, C. 8841, C. 8852, C. 9202. Left humeri. The (limeusion.s (in ceutimetre.s) of some of tlie humeri enumerated above are: — 0.815.5. C. 924.3. 0. 8150. 0.8855. 0.8841. 0.8852. M.8819. M, 8820. M. 8.392 a. M. 8.392 5. Extreme length 57-8 oT-O .54-2 53 ()1'5 55 53-8 52 52-5 50 Width of liead 14 12-8 12-4 12-5 app. 14-9 11-8 12-3 11-5 12 + 11-4 „ distal articulation . 15'5 16-4 151 13-8 16-9 13-7 14 + 14-2 14-3 13-6 „ middle of shaft . 13 12-4 12 12-3 13-3 11-5 10-G 9-9 9-8 10-1 Createst v\ idth at distal end (with supinator ridge) , . 21'3 23-2 23-5 22’2 24-1 21-5 21-0 18-1 18-G 19-5 C. 8891. Ilir (see above) (text-fig. 20). J’yci^ented h// IE. K. de Winton, J'Jsij., 1002. M. 8836. Left scajihoid. Presented hy the EyyjPian Government, 1004. C. 7944, C. 9003, C. 9013. Left scaphoids. The dimensions (in centimetres) of the above sca}ihoids are : — M. 8470. M. 8836. C. 7944. C. 9013. C. 9003. Length of posterior border ... 8-5 10 7 8*6 8-6 ,. proximal articulation . . . . ... 5 6 4-7 5-1 5*5 ,, distal articulation 8-,5 (>‘7 7 app. 7*5 Presented by tdie Egyptian Government, 1002. Presented hy the ILgyptian Government, 1004. Presented hy the Jdgyptian Government, 1004. Presented hy the Egyptian Government, 1004. C. 8936. Light lunar (text-fig. 21). C. 8390. Light lunar. M. 8404. Left cuneiform (text-fig. 22). M. 9095. Imperfect right and left cuneiforms. M. 9096. Small left cuneiform. C. 9012. Light cuneiform. C. 8106, C. 9037, C. 7955. Cuneiforms. M. 9097. Left pisiform. C. 7948, C. 7991, C. 8370, C. 9310. Lisiforms. M. 8470. Light magnum, associated with ])ortions of skull of the same nnmbcn- (see above). J^resented hy lib E. de Winton, Esq., lOO.'b M. 9098. Right magnum of larger individual. Presented hy the Egyptian Government, 1004. C. 9435. Left magnum of very large individual (text-fig. 23 ). M. 8421. Light maonum. M. 8405. Left magnum. C. 8093, C. 8406. Two specimens of the magnum. M. 8470. Left unciform associated with portions of skull of the same uumb('r (sc'c above) (text- fig. 24). M. 9099. Left unciform. M. 9100. T wo right uuciforms. J’ resented hy lib hi. de Winton, Esq., lOO.'b Presented Ip the Egyptian Government, 1004. Same history. AES INO ITIIEEI UM ZITTEIA. 77 C. 7943, C. 9031, C. 9048. Uncirorins. M. 8421, M. 8837. ? Trapezoids. C. 7946, C. 7981, C. 8397, C. 9040, C. 9431. ? Trapezoids. M. 8470. Fourth metacarpal, associated with the skull &c. of the same number (text-fig. 19). 1‘reserdeil hij IF. E. de Winton, Esq., 1903. M. 9101. Fifth metacar})al (text-fig. 19). C. 7968. Fifth metacarpal (text-fig. 25). M. 9102. Two fifth metacarpals. M. 8403. ’Third metacarpal. C. 7947, C. 7974, C. 7978, C. 8343, C. 8407, C. 9083, C. 9274. ? Third metacarpals. C. 8405, C. 9237. ? Second metacarpals. The collection in Cairo also includes numerous other specimens of metacarpals. C. 8413. Pelvis of very large individual (? A. a7id7'ewsi). This specimen is quite complete and is figured (text-figs. 20, 27) and described (pp. 47-49). M. 8812. Pelvis of a smaller individual. Presented hj the Egyptian Government, 1904. M. 8395. Right os innominatum. Presented by the Egyptian Government, 1903. M. 8492. Right ilium. Presented by the Egyptian Government, 190:5. The Cairo Museum also contains several other more or less nearly perfect pelves of this species. Greatest width between outer angles of ilia „ „ of ilium (from upper to outer angle of crista) "Width between upper (sacral) angles of ilia „ of pelvic opening Length of ischio-pubic symphysis Long diameter of obturator foramen Short ,, ,, ,, Length from symphysis to ischial tuberosity Long diameter of acetabulum Short „ „ Distance between the centres of the acetabula Width of ilium immediately above acetabulum „ pubis at middle of obturator foramen „ ischium „ „ „ Length from posterior end of symphysis to upper angle of ilium Distance between ends of the ischial tuberosities es are : — C. 8413. M. 8812. Ill 74-5 60-5 IG 10 41-0 11-5 15-2 14-7 6-2 23-5 11-4 9-G 9-9 61 50 15-1 7-4 4-7 5-8 67 57 ;37;5 29 C. 8859. Right fenuir (text-fig. 28). M. 8810, M. 8811. Right femora. Presented by the Egyptian Government, 1904. C. 8146, C. 8149. Right femora. C. 7928, C. 7933, C. 8148. Left femora. 78 TEKTIARY VJ-]RTEI51?ATA OF THE FAYCm. M. 8466. Lofi fcimir. J^rexe/ited hi/ II7 7'A de l(7?;/on, J'Jsij., 1903. M. 8396. Small femur and u])i)er half of another specimen. Presonled hij the J'Ji/i/pt'ian Government, 1902. The dimemsions (in cenlimetr('.s) of the ahove femora are : — C. 88.50. M.8811. C. 8140. M,S810. 0.814(1. C.8148. M. 84(1(1. C. 703.3. 0. 7928. I.englli 75 08 5!t 57-8 5:}-3 75-8 71-9 ()(i’3 58-5 Diameter of head .... 12 2 1 1 -5 10-8 0 0-2 12 13-4 12 10-7 Width of middle of shaft . 1 0*7 IM 10-2 9-6 8-7 13-2 13-(; 11 10 proximal end of bone .... 25 21-5 19-7 15-5 17 23-3 21 21 distal articulation 13-7 14-5 12-5 1 t l(i-(i 14 15-1 12-7 snpracondvlar ex- paiisioii . IS 17 1.3'5 14-2 13-1 17-5 18-8 16'5 16 M. 8400, M. 9106. Kinht patelhe. C. 9006, C. 9022, C. 9030, C. 9244. Right ])atellm. M. 8400 a, M. 8488, M. 8838. Left jiatellae. Presented hy the PJyyptian Government, 1903. C. 7960, C. 8373, C 9025. Left ])atellae. The dimensions (in centimetres) of some of these patellie are : — M. 91 or.. C, OOOG. C. t(030. M. 8400 «. C. 9025. Length 17-2 I(r5 17-3 15-5 of articular surface 10-4 8 9-1 9 7-G Width .... 10-5 10-4 10-0 10-4 9-7 51. 8397 a. Right tihia. Presented hy the Eyyptlan Government, 1902. C. 8171, C. 8874, C. 8878, C. 8880. Right tihiaj. C. 8165, C. 8876-7. Left tibiae. K. 8397 b. Left tihia. Presented hy the PJyypt/an Government, 1902. M. 8813-14. Left tihiiC. I’resented by the KyypUan Government, 1904' The dimensions (in centimetres) of the ahove tihiie are: — C. 8874. C. 8878. C.8171. C. 8880. C. 8877. C. 8105. M. 8813. M.8814. 0. 8870. J.ength 39-9 37-7 32-9 28-6 42 41-5 38-7 33-8 33 Width of proximal end . 15 14-3 11-5 11-ii 16-3 15-7 15'5 14 9 18 „ distal end . . 14 1L8 app . 9-2 9‘5 a|)[) . 9(?) 13-3 13-5 13 11-7 ,, middle of shaft . 7-9 7-t 5*5 5-8 8-5 8’5 6-6 ()*5 (;•9 M. 9107. Left fibula. Length 41 cm., width of distal end 9‘3 cm. I’resented hy the Kyypt 'mn Government, 1901. C. 8889. Right fibula. Length 37’7 cm., width of distal end IP) cm. A K !S I XO IT 1 1 K HI UM Z i 'I'TK 1.1 . 70 M. 9108. ( *;ist of tlio iibovo spociiiien. M. 8859. Distill ends of two flbnlie. I’resented hy the I'hjyptian Cjocermnenl, l‘JU-1. M. 8402, M. 8844 (2), M. 9103. JM^lit aslra^iili. 1* reaenled hy the Egyptian Government, IIJOI. C. 8398, C. 8403, C. 9027, C. 9054. Right astragali. M. 8402 a, M. 8488, M. 8844 a, M. 9104. Left astragali, the first figured in text-lig. ;52, 2. J ‘resented hy the J^hyyptian Governnient, 1901. C. 8382, C. 9016, C.9029. Left astragali. The dimensions (in centimetres) of some of the above astragali are : — C. 8398. C. 9027. AI.8402a. M. 8844. M.9104. C. 90,54. Greatest width of tibio-fibular surface ll-« 11-4 lU-5 lu 0-2 8-G „ „ naviculo-cuboid surface .... 12-4 •} 10-6 10 -,5 8-8 0 „ „ calcaneal surfaces 10-4 10-2 9-4 !)-o 8-2 8 „ „ the bone as a whole 13-4 11-2 10-5 11-5 10 10 Thickness from middle of tibial surface to middle of calcaueal surface 6 G-() G-1 G 4-8 .■)-4 M. 8843. Left calcaneum of very large size. Presented hy the Egyptian Government, 1904. C. 9041, C. 9062. Left calcanea of very large size. C. £033, C. 9267. Left calcanea. M.8843 a, M. 9105. Left calcanea, the second figured in text-fig. 32, 1. C. 9267. Left calcaneum. C. 7949. Right calcaneum of large size. C. 7980, C. 7994, C. 9266. Eight calcanea. The dimensions (in centimetres) of some of the above calcanea are : — M. 8843. C.9041. C. 90()2. C. 9207. M. 9105. M. 8843 «. Extreme length . . . 15 14-7 14-1 11-2 11 8-9 AVidth of astragalo-fibular surface . . . . . . 13-5 12-5 12-9 10 CD 13 11-5 „ cuboid surface ... 3-8 3-7 3-G .4-G 8 Height to top of astragalar surface . . . . . . 10 10 9-8 G 9-2 .s It is probable that some of the largest of these calcanea belong to ^1. andreicsi. M. 8421. Left navicular (text-fig. 33). C. 9017. Left navicular. C. 7969. Right navicular. The dimensions (in centimetres) of two of these naviculars are : — iM.8421. C. 7909. 8-0 5-5 4-0 3'5 10-8 8-5 AVidth of astragalar suil'ace Greatest depth .... AVidth of distal surface . so TEliTTAKY VEKTEBKATA OF THE FAYtM. M. 8405. cuboid (text-fig. 34). C. 8327. Higlit ctd)oi(l. M. 8834. Loft cul)oid. C. 9024. L(4't cnl)oi(l. C. 7971, C. 9036, C. 9059. Cuboids. TIu' diiuei).sions (in centimetres) of some of these Width of astragalar surface ,, distal end of bone (Greatest depth C. 9051. (?) (Middle metatarsal (text-fig. 35, 2). C. 9273. Tjuteral metatarsal (text-fig. 35, 1). M. 8413. Middle metatarsal. M. 8403 (2). Middle metatarsals. M. 8403 a. Lateral metatarsal. C. 9061. ? Metatarsal. Presented hy the Kyyptian Government, 1904. Presented hy the Eiryptian Government, 1904. cuboids are : — C. 8327. C.7071. M. 8405. M. 8834. 5-2 4-7 4-.5 4-3 G-G 5-2 6-5 5-8 4-0 4-3 3-7 P resented hy the Eyyptian Government, 1902. Presented hy the Eyyjdian Government, 1902. Arsinoitheriuni andrewsi, Lankester. [Plate IV. figs. 2, 3 ; text-fig. 38.] 1903. Arsinokherium andreivsi, E. E. Lankester, The Sphere, Sept. 1903, quoted in Geol. Mag. [4] vol. X. p. 531. 1904. „ ,, ( '. AY. Andrews, Geol. Mag. [5] vol. i. pi. vi. figs. 1-3. Type Specimen. — A left maxilla Avitli 2-?n. 3 and the associated mandible tvitli i. 3, three cervical vertebrte, the distal half of a left humerus (text-fig. 38), and a right ulna ; British Museum. This species is distinguished from A. zitteli by its much greater size, its dimensions l)eing nearly half as large again. The mandible attains a length of about 73 cm. ; the length of the three ])osterior upper premolars and the molars taken together is 34'5 cm. The lower ])remolars a})pear to have their crowns somewhat more compressed from witliin outwards than is the case in the ty])e species, otherwise the dentition is closely similar in the two forms. T'he enormously massive humerus has its condyles rather more strongly develo[)ed than in the other species, and the Lattening of the ])osterior face of the lemur seems to be even more strongly marked. Form. & Loc. — IT uvio -marine beds (Upper Eocene) : north of Birket-cT-Qurun. AKSINOITIIEKIUM ANDliEWSI. 81 s.r.' Texl-lig. 38. Left humerus of Arsinoitlierium andrewsi : A, from behind ; B, from front. (f., deltoid crest; i.c., inner condyle; o.c., outer condyle; o.f., olecranon fossa; s.r., supinator ridge; tr.f., inner trochlea ; ai. 1, 2, 2’7 cm. (in M. minor, 3 cm.). Teeth considerably narrower than in M. minor, owing to the slight development of the inner cusp and of the postero-internal shelf. Form. & Loc. — Fluvio-marine beds (Upper Eocene): north of Birket-el-Qurun. M. 8434. Anterior portion of right maxilla with the canine, first preraolar, and the greater part of the second premolar. Type specimen. The canine is almost unworn ; it consists of a fairly high sharp main cusp, and a small anterior cusp, from which the cingulum, which is strongly developed, runs round the inner face of the tooth to its posterior angle. The outer half of pm. 1 is similar, but here there is a strongly developed antero-internal cusp and a postero-internal heel. Pm. 2 is incomplete, but it can be seen that it had a large antero-internal cusp and a postero-internal cusp on the cingulum. The lengths of the three teeth (in centimetres) are : c. 1'3 ; pm. 1, 1‘4 ; pm. 2, 1‘4. Total length of the three, 4 cm. C. 10010. Right upper m.2, probably of this species, figured on PI. VI. fig. 5. This molar is very like that of Megalohyrax minor, but is smaller and has the outer main cusps forming slightly greater projections on the ectoloph. The length of the ectoloph is 1‘85 cm., in M. minor 2'6 cm., and in Saghatherium magnum 1'4 cm., so that there can be no doubt that this, like the other specimen, indicates the existence of another species intermediate in size between S. magnum and M. minor, and to this the name Saghatherium majus may also be applied. Length 1'9 cm., width 1'9 cm. M. 8453. Plaster cast of the above specimen. Made in the British Museum. M. 8879. Posterior portion of right ramus of mandible with the greatly worn m. 2 and m. 3 in situ. The length of m.2 is 1‘3 cm., that of m. 3, 1'7 cm. ; the depth of the ramus beneath m. 3 is 4 cm. 92 TERTIARY VERTEBRATA OF THE FATtM. Genus MEGALOHYRAX, Andrews, [G(‘ol. Mag. [4] vol. X. (1903), p. 340.] ITyracoids of large size. The postero-internal cusp of the posterior premolars well developed, at least in pm. 4. In some s])ecies the two posterior incisors have two roots. Megalohyrax eocsBnus, Andrews. [Plate VI. figs. 1, 2; text-fig. 39.] 1903. Megalohyra.r eoccenus, C. W. Andrews, Geol. Mag. [4] vol. x. p. 340, fig. 1. Type Specimen. — Right maxilla with the canine, premolars, and molars (PI. VI. fig. 2) ; British Museum. The type species, in which the length of the molar and premolar series together is ICr2 cm., that of the molars alone S'G cm. Form. & Loc. — P’luvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. Devtition (PI. VI. fig. 2). — The teeth are brachyodont and form a slightly curved series, which, so far as the molars and premolars are concerned, is traversed from end to end by a well-marked valley lying between the ectolophs of the teeth on the one hand and the inner cusps on the other. In the upper molars the ectoloph is W-shaped, the parastyie and mesostyle being strongly developed, while the metastyle seems to have been wanting except in the last molar. In this tooth there is a small posterior lobe formed by the metastyle [mt.s.) and hypostyle {li.s.), but it is much smaller than in Saghatherhun and the tooth is consequently more quadrate in outline. Behind the parastyie and mesostyle in m. o and behind the mesostyle at least in m. 2 there are small accessory styles [ac.s.) on the cingulum : these have been observed in this species only. The main cusps of the ectoloph {a.e. and p.e.) are V-shaped and form no projection on the outer wall of the tooth. The inner cusps are large and wear to a V-shaped surface, the anterior arms of the V’s running outwards and forwards to the parastyie and anterior end of the postero-external cusp respectively. The cingulum is slightly develojmd on the inner half of the anterior face and on the anterior half of the inner side of the tooth. The premolars arc all simpler than the molars. The outer half of pm. 4 is wanting, but pm. 3 is complete. Its ectoloph is composed of three elements, an anterior parastyie (j)S.) and a pair of subequal cusps sei)aratcd externally by a slight fold. On the outer side of the tooth there is a small tubercle on the cingulum, most {wobably the mesostyle [ms.). The inner half of the tooth consists of a large antero- internal cusj) exactly similar to the antcro-internal cusp of the molars and like it giving a V-shaped surface in wear. Behind this on the extreme edge of the postero- MEGALOIlYliAX EOCAiNUS. 93 internal angle of tlie tooth is a small element, which is larger \\\ pm. 4 than h\ pm. 3, and absent in tlie other ])remolars, in wliich the postero-internal angle of the tooth forms a shelf-like surface bordered by the cingulum. The canine is much worn, but seems to consist of a single blunt cusp borne on two roots. Its posterior border is in contact with the anterior premolar. In front of the canine the edentulous alveolar border of the maxilla extended for some distance. 'I'he width of the palate between the last premolars is C'4 cm., and anteriorly it must have been very concave from side to side. Shdl (PI. VI. fig. I ; text-fig. 39). — A premaxilla (C. 10009) of extraordinary form (PI. VI. figs. 1, 1 a), bearing a large tusk-like anterior incisor and the alveoli of two other teeth, may be ascribed with considerable confidence to the present species. This specimen was originally referred provisionally to the problematical Phiomia but subsequently it was placed in its present position and a figure showing its probable relationship with the maxilla of M. eocwnus was given f. The bone consists mainly of a socket for the great rootless incisor-tusk [i. 1) which curves round almost in an arc of a circle. The anterior border of the bone immediately above the base of the tooth is rounded and continues so for some distance up : it then becomes sharp-edged and the inner face is marked by a rough surface for union with another bone — the nasal. The actual hinder border is broken away. The outer face is rendered strongly convex in its upper portion by the socket of the great tusk-like incisor, but beneath this it is concave from above downwards, the bone thinning suddenly towards the alveolar border. The inner face beneath the surface for the nasal is marked by two broad shallow grooves and its lower edge is roughened for union with the overlapping maxilla. The palatine process (pl.p.) is a short stout projection which united in the middle line with its fellow of the opposite side ; the sutural surface is deepest behind ; it does not extend quite so far forwards as the anterior border of the tooth, but projects some distance behind its posterior angle. The great first incisor {i. I) is a rootless tooth, the socket of which perhaps extended even into the maxilla. It is triangular in section, one angle being anterior but rather nearer to the outer than the inner side, the outer face being narrower than the inner. The anterior faces of the tooth are both enamel-covered, the enamel being marked by slight longitudinal striae. Both these faces are convex on the whole, but are marked by a slight longitudinal groove in the middle, that on the antero- external face being the best marked. The posterior face is without enamel ; its wear-surface extends from the sharp tip of the tooth to within a short distance of the alveolar border. Immediately behind the socket of this tooth there is a deep depression formed by the converging edges of the alveolus which meet and form the * Andrews and Beadnell, ‘A Preliminary Note on some new Mammals from the Upper Eocene of Egypt ’ (Cairo, 1902). t Geol. Mag. [4] vol. x. 1903, p. 340, fig. 2. 94 TERTIATIY VERTEBRATA OF THE FATOM. thin alveolar border. About 2-5 centimetres behind the large tooth are two small alveoli for a double-rooted incisor (/. 2), and behind this again the remains of another double-rooted tooth, the third incisor [i. 3). The presence of these peculiar double- rooted iucisor-tceth seems to show that the same causes, whatever they may be, which gave rise to a doid:)lc-rootcd ju’emolariform canine also affect the two posterior incisors, so that all the teeth behind the first incisor practically form a series of cheek-teeth. Comparison of this premaxilla and its contained tusk with the premaxilla and incisor of a recent Ilyracoid show that, as in Saglt atheriimi magnum, the two are closely similar in most respects. The presence of the two posterior incisors is just what might be expected in this early form, the remarkable thing being not the difference between the Eocene forms and recent types but their great resemblance, which shows that, so far as the front of the skull is concerned, the older forms were almost as peculiar as the modern ones. Among the specimens collected by Mr. Beadnell in 1903 is the cranial portion of a skull (text-fig. 39) which, from its resemblance to the corresponding part of the skull of Saghatherium antiquum, may reasonably be referred to a Ilyracoid, and from its size most probably belongs to the present species. The occipital condyles {cond.) are large and sharply truncated at their upper border. The foramen magnum {f.m.) is roughly quadrate in outline. Above and external to the condyles there is on either side a deep depression separating them from the strongly developed paroccipital processes which project below their level. The occipital surface widens out a little above the condyles and its upper border forms the middle portion of a high prominent lambdoidal crest, which is continued downwards and outwards on to the squamosal and is continuous with the upper edge of the zygomatic process of that bone. Just below the lambdoidal crest the occipital surface bears in the middle line a roughened ridge flanked by two smaller lateral ones ; this portion of the surface slopes somewhat backwards. Between the upper edge of the paroccipital process and the squamosal there is a slit-like foramen lying immediately beneath the lambdoidal crest; laterally and external to the slit the anterior hrce of the paroccipital region of the exoccipital is closely apposed to the posterior face of a nearly vertical ridge of the squamosal, the two limiting a well-marked groove. Between the just-mentioned vertical ridge and the iq)per border of the zygomatic process is a triangular area, at the bottom of which the auditory opening must have been ; the anterior border of this depression is formed by a prominent postglenoid process (pgl.). There is a strong sagittal crest (s.e.) running forwards from the lambdoidal ridge till it bifurcates. The temporal ridges (p.orb.) thus formed run out on to the posterior- borders of the supraorbital processes. The brain-case is strongly rounded and slightly contracted a little behind tire orbits. The frontal region (/>’.) is very broad and flat, aird closely reserrrbles the same portion of the skull of Saghatherium and llgrax [Procaoia). MEGALOIIYEAX EOC^.NUS. 95 The basal portion of the skull is f^reatly crushed, but it can be seen that the condyles nearly meet below in the middle line ; in front of them the basioccipital bears on either side a sharp ridge ; anteriorly the basicranial axis is much contracted. The glenoid surface, formed entirely by the squamosal, is very broad and fiat. Text-fig. 39. Posterior portion of skull of ? Megaloliyrax eoccenus : A, from above ; B, from behind. cond., occipital condyles ; f.m., foramen magnum ; fr., frontals ; jja., parietals ; yygl., postglenoid process ; p.orh., temporal (postorbital) ridge ; p.p., paroccipital process ; s.c,, sagittal crest ; soc., supraoccipital ; sp, squamosal. ^ nat. size. Comparison of this skull with recent forms shows that, not only in the shape of the frontal region but also in that of the paroccipital processes and their relations to the squamosal, as well as in the structure of the glenoid surface, it is very like the skull of Hyrax {Procmia) validus. M. 8502. Right maxilla with canine, premolars, and molars. The type specimen described and figured in the Geol. Mag. [4] vol. x. (1903), pp. 339-341, fig. 1, and also on PI. VI. fig, 2. On the whole the teeth are in a good state of preservation, but portions of the ectoloph 96 TERTIARY VERTEBRATA OF THE FATtlM. of pin. 4, in. 1, and m. 2 have l)een broken away, and m. 3 is not quite complete posteriorly. The dimensions (in centimetres) of this specimen are : — Length of tooth-series (canine, premolars, and molars) . . . 17‘8 ,, molar series 8'6 ,, premolar series 7‘6 Length. Width. m. 3 .3-7 3-5 HI. 1 pin. 4 pm. 3 jim. 2 p»n. 1 c. 3‘7 app. 3’2 3-0 2-5 1-9 2-5 2-1 2-3 1-8 1-8 1-8 1-8 1-2 C. 10009. Left premaxilla with i. 1 and the sockets of i. 2 and i. 3. Described and figured by Andrews and Beadnell in ‘ Prelim. Note on some new Mammals from the Upper Eocene of Egypt, ^ PP- 4-5, fig. 3, where it was provisionally referred to Phiomia xerriden.i. Also figured on PI. VI. fig. 1. The dimensions (in centimetres) of this specimen are : — Length of premaxilla, so far as preserved 12‘0 Depth of premaxilla beneath i. 2 5-0 Length of palatine process 2-8 Length of tusk (incomplete posteriorly) in straight line . . . 14'0 „ „ projecting from alveolus 5'0 Antero-posterior diameter of tusk at alveolus 2-2 Lateral diameter of tusk at alveolus . . . . ' P4 M. 8144. Plaster cast of the last specimen. Made in the British Museum. C. 8801. Posterior portion of greatly crushed skull, probably belonging to this species or to Jlf. minor (text-fig. 39). The dimensions (in centimetres) are : — Width of condyles 4-9 „ at base of zygomatic process of squamosal .... 15-0 ,, (greatest) of brain-case 7’0 Approximate width between supraorbital processe.s .... Hi M. 8872. Plaster cast of the above specimen. Made in the British Museum. Megalohyrax minor, Andrews. [Plate VII. figs. I, 2, 3.] 1004. Afegalohprax minor, C. W. Andrews, Geol. Mag. [5] vol. i. p. 2 LI. Type Specimen. — Left maxilla with the molar and premolar series ])reserved (PI. Vll. fig. I) ; Geological Musenm, Cairo. The length of the molar and ])remolar series together is 13 cm., that of the molars alone 7'5 cm. M EGA LOl r Y RAX M IN( ) R 07 Form. & Loc. — Fliivio-inarine Reds (Upper Eocene) : iiortli of Birket-el-Qurun. Upper Dentition (PI. YU. fig. 1). — Exce])t in tlieir smaller size the upper molars of this species closely resemble those of M. eoewnns, the only notable differences being the absence of the small accessory styles of the outer face of m. 1 and m. 2, and the fact that the main outer cusiis form slight projections on the ectoloph. The premolars, on the other hand, differ more considerably from those of the larger species, the chief point of difference being that they are more simple. Thus in pm. 4 there is a fairly well- developed postero-internal cusp, but it is smaller than in the corresponding tooth of M. eoccenus, and the tooth is less quadrate in outline. l\\pm.?i the postero-internal cusp is practically absent and its position is occupied by a shelf-like projection ; the same is the case with the other premolars. In pm. 1 the antero-internal cusp also is much smaller than in M. eocamus, and approximates in form to the canine of that species. In fact, each of the premolar teeth of the present species resembles the next tooth in front of it in M. eocceniis, rather than the corresponding tooth. It can be seen that the posterior border of the zygomatic process of the maxilla is about opposite the hinder lobe of m. 3. Lovoer Dentition (PI. VII. figs. 2, 3). — The collection at Cairo includes portions of the right and left rami of a mandible which probably belongs to this species and possibly to the same individual as the type specimen. The portion of the left ramus preserved contains the two anterior incisors (fig. 3, I, i. 2), the third and fourth premolars, and the first and second molars. The right half (figs. 2, 2 a) includes the three posterior premolars and the molars. Unfortunately, the two rami do not join, some fragments of bone being wanting, and in the left ramus the alveolar border is incomplete between the second incisor and the third premolar, so that the exact dental formula cannot be determined. The incisors (fig. 3), of which, probably, only two pairs were present, are of somewhat peculiar form, and in the present specimen they are considerably worn. The crowns are broad and spatulate, and in the case of the anterior one [i. I) somewhat flattened on the anterior face. The Avear-surface in each forms a narrow band along the whole of their upper edge. They show no trace of the peculiar pectinate form seen in the incisors of the recent Hyraces, but it is by no means impossible that this may have existed in the unworn tooth. The cheek-teeth (fig. 2), so far as known, form a closed series. The molars consist of two crescents : the postero-internal end of the anterior crescent terminates in a cusp [ai.) which is joined posteriorly with another small cusp, which partly closes the opening of the posterior crescent. This cusp is the metastylid [msd.), and is strongly developed in all the teeth from the third premolar back. In pm. 2 it is not present. The third molar has a small talon {t.) giving a crescentic surface in Avear. The cingulum is fairly Avell developed on the outer side of the last premolar and in the molars. 0 98 TEKTIARY VERTEBRATA OF THE FAYOM. The mandibular ramus is massive and does not deepen so rapidly from before backwards as in the other members of the group. The symphysis is short and extends to the level of the posterior lobe of 2)m. 2. Its ventral surface is marked by a slight prominence, behind which, and forming the ventral border of the mandible for a short distance, is a strong ridge for the attachment of a powerful muscle (1 the mandibular) : the same arrangement is very well marked in Ilijrax {Procavia). 'I'lie ascending ramus is broad ; its inner border is formed by a ridge continuous with the alveolar border, while the outer rises on the outer face of the ramus beneath m. 3. The inner border, about 3 cm. above the talon of m. 3, turns sharply outwards and joins the outer border to form the thin anterior edge of the coronoid process: exactly the same arrangement may be seen in the mandible of Ihjrax {Procavia). At the bottom of the fossa thus formed behind the last molar, a foramen opens into a ])assage, the other aperture of which is on the inner face of the posterior portion of the jaw. C. 8818. Left maxilla with molar.s and premolars. Type specimen described in the Geol. Mag. [5] vol. i. (1904) p. 213. Figured on PI. VII. fig. 1. The dimensions (in centi- metres) of the specimen are : length of m. 3, 2'9 ; m. 2, 2'G ; m. 1, 2’1 ; fm. 4, 1'7 ; pm. 3, 1’5; pm. 2, 1’4 ; pm. 1, 1%5. The total length of the molar-premolar series is 13, that of the molar series alone 7'5. >1. 8870. Plaster cast of the above specimen. C. 8822-3. Portions of a mandible including the greater part of the right ramus with pm. 2-4 and m. 1-3, and the anterior portion of the left ramus with part of the symphysis containing pm. 3-4, m. 1-2, and in front tw'o incisors, probably i. 1 and i. 2. Figured on PI. VII. figs. 2, 3. The dimensions (in centimetres) of the teeth are ; — Length. Width. m.3 3‘3 2 m.2 2-3 1-8 m. 1 1-9 1-6 pm. i 1‘8 I’G pm. 3 l‘(5 1-4 pm. 2 1'7 IT Lengtli of series from pm. 2-m. 3 inclusive, 12-7 cm. The widths of the crowns of the incisors are : i. 1, IT cm. ; i.2, PG cm. M. 8871. Plaster casts of the above specimens. M. 9220. Left ramus of mandible with m. 2-3, pm. 3, and part of pm. 4. MCERITIIERIUM. 99 Suborder PROBOSCIBEA. Bones of skull, particularly those of the cranial region, with a strong tendency to the great development of the diploe ; an alisphenoid canal ; no condylar foramen. Molars lophodont, passing from a bilophodont, brachyodont type in the earliest forms to a very hypsodont condition with numerous transverse crests in the later. Second upper incisors enlarged to form tusks. Feet, where known, pentadactyl and digiti- grade with taxeopod structure: a centrale in the carpus, at least in the young. No entepicondylar foramen in the humerus. Radius and ulna, tibia and fibula complete and separate from one another. No third trochanter in the femur. Astragalus articulating distally with the navicular only. Calcaneum with large fibular facet. Family MGERITHERIID.F:. Comparatively small animals about as large as the Tapir. Skull with greatly elongated cranial region, the orbits being placed far forwards and the nares nearly terminal ; probably a small proboscis was present. More than one pair of incisors in upper and lower jaws : molars quadritubercular and bilophodont. Genus MCERITHERIUM, Andrews. [Tageblatt des V. Internationalen Zoologen-Congresses, No. 6, p. 4, Berlin, 1901 (Verhandlungen, p. 528).] Dental formula : — i. | ; c. ^ | ; m. 3. The second incisors in both jaws greatly enlarged and tusk-like. The last premolar not bilophodont ; molars bilophodont. This genus is represented by several species, of which Mcerithermm lyonsi is the type. It is found in both the Middle and Upper Eocene deposits of the Fayum. Skull (PI. VIII. ; PI. IX. fig. I ; PL X. figs. 3, 4 ; text-fig. 40). — The following description of the skull is founded mainly upon a nearly complete specimen (PI. VIII. ; PI. IX. fig. I) belonging to a young individual, in which the second incisors and third molars are still uncut. This skull (C. 7867) is from the Upper Eocene beds, but does not seem to differ in structure from the less nearly perfect specimens from the Qasr-el- Sagha beds (Middle Eocene). In some cases references will be made to some of these other specimens wdien they supply more satisfactory information on any point. In its general form the skull is long and somewhat depressed, wffth very strong and o2 100 TEllTTAIiY VEllTEr5EATA OF THE FATDM. ])romiiient zyg'omatic arches. The cranial region is nearly twice as long as the facial region. The dorsal surface is straight or very slightly concave from before backwards, the highest portions of the skull-roof being the point of junction of the lambdoidal and sagittal ridges posteriorly and the nasals anteriorly. The anterior prominence is probably duo to the deepening of the premaxillm and maxillm, resulting from the great enlargement of the second pair of incisors. The orbit is very small and is open Text-fig. 40. Restored skull and mandible of Mceritlicrium Itjonsi : A, from above ; 13, from left side. ant.orh., antorbital foramen; ex.oc., exoccipital ; //•., frontal; ju., jngal ; mx., maxilla; nasal; l>a., parietal; p.mx., premaxilla; post-tym[)ainc process of squamosal; s.oc., supraoccipital ; Sly., squamosal, i. 1, i. 2, {. 3, incisors; c., canine; yu/n 2, pm. 3, pm. 4, jiremolars ; m. 1, m. 2, m. 3, molars. About 1 nat. size. ])osteriorly ; the postorbital process of the jugal is fairly well marked, but that of the frontal is practically obsolete. The large anterior nasal o])ening is situated near the end of the snout, but is widely separated from the alveolar border, the ])remaxilke being greatly deepened to carry the large incisors (Tl. IX. fig. 1 and I’l. X. fig. 3). d'he internal narial opening in this specimen is opposite the front of tlie still uncut ]\KEKIT1IERIU.M. 101 third molar, but in older skulls in Avhich this tooth has come into wear the openinj^ is opposite its hinder end. The palate is narrow and the cheek-teeth are arranged in straight and parallel series. The hasioGcipital (PI. VIll. fig. 1 a, ho.) is broad and regularly convex from side to side, at least posteriorly. Anterioily the crushing that has been undergone obscures both tlie form of the bone and its relations to the hasisphenoid, nor are these points better seen in other specimens. Posteriorly it is deeply notched by the ventral border of the foramen magnum, and laterally it forms the lower ends of the occipital condyles. External to the basioccipital is a large foramen, in part no doubt the foramen lacerum posterius (f.l.p.) ; the postero-internal angle of this opening forms a notch at the point of union of the basioccipital and exoccipital bones, probably representing the condylar foramen. The exoccipitals {exo.) are very large, and the condyles are strongly convex from above downwards, but less so fnun side to side. Above the condyles and over the foramen magnum the bones rise nearly vertically, meeting in the middle line in a suture about 3 cm. long, thus excluding the supraoccipital from the foramen. Laterally and ventrally the exoccipital forms the inner and lower portion of a great flange of bone, of which the outer part is formed by the squamosal. This plate of bone adds greatly to the width and depth of the occipital surface of the skull, and its ventral angle is the equivalent of the paroccipital process of the exoccipital [p-p.). In the later type, Falaiomastodon (PI. XII. fig. I), the exoccipital region is drawn out in such a w^ay that the condyles project to a much greater degree behind the occipital surface, Avhich slopes forwards instead of being nearly vertical. At the same time the flange of bone just described is, as it were, pulled out to form the surface lying between the hinder border of the glenoid cavity and the occipital condyles, w^hicli surface is likewise constituted by the squamosal and the paroccipital portion of the exoccipital (see PI. XII. fig. p.p.). In fact, the difierences betw'een this region of the skull in Moeritherium and Palceomastodon are just such as would be produced, if the skull of the former consisted of a plastic material and the condyles were pulled backwvards so as to lengthen the interval between them and the glenoid surface. As will be pointed out in the description of the skull of Palceomastodon, the paroccipital process is there represented by a blunt tuberosity only. The supraoccipital {soc.) is a large somewhat shield-shaped bone. Its upper border, forming the upper portion of the lambdoidal crest, is nearly semicircular in outline. At its summit the bone is greatly thickened (PI. VIII. fig. 1), and sends forwards a triangular process between the hinder ends of the parietals, but there does not appear to be any separate interparietal. The occipital surface is raised in the middle line into a vertical ridge, on either side of w'hich there is first a slight concavity and then a convexity : this median ridge with its accompanying lateral depressions is the predecessor of the great depression and ridge for muscle-attachment found in 102 TEETIAKY VEUTEBEATA OE THE FATOM. PalaeomastoRon and the later Proboscidea. The supraoccipital, together with that |)ortion of the exoccij)itals above tlie foramen magnum, forms a sort of escutcheon- sliapcd area, which ])rojects a little behind the rest of the occipital surface formed by the exocci])ital-squamosal plate above referred to. One peculiar feature is, that l)etween the lower end of the lambdoidal border of the supraoccipital and the occipital |•('gion of the squamosal, a small triangular process of the parietal is interposed, this l)one thus assisting in the formation of the occipital surface (PI. VIII. fig. 1 pa., and ri. X. fig. 4 A, ])a.). 'fhe squamosal [sq.) is a very large and massively constructed bone, in which it ap])ears that the development of the diploe, carried to such a high pitch in later types, has already begun ; and on the upper surface of the bone above the auditory opening there are several foramina (PI. VIII. fig. I, /or.) communicating with the interior, just as in l^alceomastodon : this inflation of the squamosal is especially well shown in the type skull of M. gracile (PI. XVII. fig. 2). The posterior portion of the bone forms the outer part of the occipital surface: internally it unites with the exoccipital, but it is excluded from contact with the supraoccipital by the process of the parietal above referred to. This post-tympanic region of the squamosal forms the posterior wall of the external auditory meatus (Pis. VIII., IX. fig. 1, e.a.m.), and closes it ventrally by uniting wdth the posterior edge of the glenoid surface, just as in Palceomastodon and the later Proboscidea. The lower border of the post-t}'mpanic process {ptg.) extends considerably below the glenoid surface and forms a sort of spurious postglenoid process ; internally it is wedged between the glenoid surface and the paroccipital process of the exoccipital. Superiorly the squamosal unites with the parietal, the suture wdth which runs down to about the middle of the temporal fossa, but, owing to the condition of that part of the skull, cannot be traced further. The zygomatic process is large and projects strongly on the side of the skull. It is triangular in section : the upper edge is continued upwards on to the side of the skull, forming the lower portion of the lambdoidal ridge ; the outer edge turns inwards and forms the ])osterior border of the glenoid surface. This surface is very large, extending from the outer edge of the zygomatic process inwards almost to the level of the pterygoid processes. It is concave from side to side and strongly convex from l)efore backwards, ])articularly anteriorly. A portion of its antero-external border is formed by the hinder end of the jugal. The posterior portion of the glenoid surface is borne uj)on the shelf- like projection, of which the upper surface forms the floor of the auditory opening. 4’he tympanic is so much crushed and obscured by matrix that neither it nor the foramina in its neighbourhood can be described. The ]>arietals {paf, as already described, send back a short ])rocess on to the occipital surface on either side. Above they unite with the su})raocci])ital, which sends a process between them for some distance. In front of this they meet one another in the middle line and form a not very prominent sagittal crest for some MCERlTIIEIilUM. 103 distance ; but towards their anterior end they again diverge, and the sagittal crest also divides into the feebly marked supratemporal ridges, which are continued forwards on the froiitals, terminating in tlie neighbourhood of the orbits. Ventrally the parietals unite behind with the squamosals and probably with the alisphenoid ; farther forwards with the frontals, which they overlap anteriorly to a considerable extent in a sort of squamous suture. The frontals (fr.) are large bones which meet in the middle line, forming the flat roof of the skull between the obscure supratemporal ridges, which terminate over the small orbits, though there are no distinct postorbital processes. Anteriorly the frontals are separated by the nasals, which run back for some distance between them ; they end in front in a rounded point about on a level with the anterior border of the orbits, and are separated from the premaxillae by a short interval, owing to the fact that the nasal sends down a process which joins the maxilla, d'he lachrymal cannot be made out in any specimen examined, this region being usually very badly preserved. In one case there is on the edge of the orbit a small tubercle presumably borne on the lachrymal, but there is no evidence of a lachrymal foramen. The nasals (na.) are fairly large bones, which run back some distance between the frontals. As they pass forwards they widen out, till at their widest point they form a short suture with the maxillae. In front of this they again narrow between the upper ends of the premaxillae. Anteriorly they terminate in bluntly rounded ends, which slightly (about 7 mm.) overhang the anterior narial opening. The difference between this region of the skull in Palceomastodon and Moeritherium seems to be due to the shifting back of the nares (consequent on the development of the proboscis) in the former, which leads to the reduction of the nasals and the carrying back of the facial processes of the premaxillae till their upper ends meet the frontals and exclude the nasals from contact with the maxillae. The 'premaxillm {pnx.), which together form the broad blunt snout, are chiefly remarkable for the depth and solidity of their alveolar region, resulting from the great enlargement of the tusk-like second incisors. The chief consequence of this modification is, that the floor of the narial cavity is raised much higher above the level of the alveolar border than usual, and the distance betw'een it and the palate is greater. In the skull figured in PI. VIII., a portion of the anterior region of these bones overlying the median pair of incisors is broken away, but in another specimen the upper surface of this anterior region is seen to be deeply grooved in the middle line, the depth of the groove being increased by the presence of prominent ridges on either side of it ; outside these again, and separated from them by slight depressions, are the prominences formed by the large alveoli of i. 2. The upper surface of the bones forms the floor of the nasal cavity, which, owing to the shortness of the nasals, is exposed for some distance. The presence of the ridges and grooves on the front of the snout may indicate that there was a mobile upper lip or short proboscis requiring 104 TEHTJARY YERTEBRATA OF THE FAYCM. extensive muscle-attaclnneuts. 4'lie facial processes of the premaxillaj form the lateral borders of the nasal opening ; above they expand slightly and unite in suture with the nasals. The suture with the maxilla runs downwmrds and forwards and crosses the alveolar border immediately behind i. 3. The palatal region is almost completely concealed by the forward prolongations of the maxillm, which will be referred to belowc The 'inaxillw [mx.) are very large and greatly elongatc'd elements ; their palatine plates are narrow and their alveolar borders are straight and parallel wuth one another. Posteriorly the palatine plates are separated by the palatines, which, in the specimen figured on PL Vlll., extend forwards as far as the level of the anterior crest of m. 1. It appears, however, that some change in the relative position of the palatines and the molar series takes place as the hinder molars come into position, for in another specimen, in which the last molar is in wear, the anterior end of the palatines is o})posite m. 2, and the posterior border of the palate opposite the hind lobe of m. 3. Anteriorly the maxillae send forwards plates of hone beneath the palatine surface of the preniaxillae, extending almost up to the sockets of the anterior incisors. This same peculiarity may be seen in the later Proboscideans, in w-hich the anterior prolongations of the maxillae may actually help to form part of the hinder border of the alveoli of the tusks, to the support of which they greatly contribute. There seems to be a single elongated anterior palatine vacuity, lying between the piemaxilhe and the slightly divergent anterior prolongations of the maxillae. The facial portion of the maxilla meets the nasal above, thus cutting off the frontal from the premaxilla by a short interval. The relations wuth the lachrymal cannot be made out, but the union with the frontals forms a long straight suture running downwards and backwards ; its posterior end is obscure in all specimens. The zygomatic process arises considerably above the alveolar border ; its base is very long, its anterior end being considerably in front of the anterior ])remolar {p7n. 2), the posterior opposite the hinder border of pm. 4. Anteriorly the process is perforated by a large antorbital foramen (PI. IX. fig. 1, w'hich opens on the face immediately over the anterior end oi pm. '2. Above it forms the floor of the orbit in front, and behind it is overlapped by the jugal. The free portion of the zygomatic process is short and stout. The jvqal {ju.) is large and forms the greater part of the zygomatic arch. Posteriorly it runs back beneath the zygomatic process of the squamosal as far as the glenoid cavity, in the formation of which it takes a small share. In front of this the bone curves gently downwards, and anteriorly it overlaps the zygomatic process of the maxilla, with which it unites in a long suture, nearly straight externally, but >*-shaped on the inner face of the arch. The anterior extremity of the bone, together with the underlying maxilla, forms a small ])ostorbital projection, which marks the posterior limit of the orbit, which was very small. The palatines {pi.}, as above described, form the hinder portion of the hard MCERITIIEEIUM. 105 palate, and extend forwards in the specimen figured in PI. VIII. as far as the front of m. 1. At their anterior end there is a pair of small posterior palatine foramina (not shown in the figure). The hinder edge of the palate is greatly thickened ; so also are the vertical plates, which, with the pterygoids, bound the mesopterygoid fossa. It seems possible that these bones helped to form the inner wall of the cavity in which the uncut germ of m. 3 lies in the specimen figured in PI. VlII. The internal narial opening is about as deep as wide, and in its roof the vomer can be seen extending back to about the level of the hinder border of the palate. The are too much crushed and broken for description ; it appears that their thickened posterior angle was about opposite the anterior edge of the glenoid cavity. Several casts of the cranial cavity have been obtained. The best of these, taken from a skull (M. 8898) which lacks most of the facial region, is figured (text-fig. 41). The brain is much larger in proportion to the bulk of the animal than is usually the case in the Eocene Mammalia, e. g. the Amblypoda ; and it is possible that the early tendency towards a considerable cerebral development shown in these primitive Proboscidea is one of the causes why the group has survived and flourished through so long a period. The olfactory lobes [o.l.) are large and pedunculate. They project forwards entirely in advance of the cerebral hemispheres, which are divided into anterior and posterior portions by a broad lateral groove (the pseudosylvian of Elliott Smith), which runs downwards and forwards {])■). The anterior (frontal) lobes {f.l.) are broad, rounded e.xternally, and somewhat compressed from above downwards. The posterior (temporal) lobes {t.l.) project considerably beyond the frontal lobes both laterally and ventrally ; they are comparatively narrow from before backwards. Posteriorly the temporal lobes are separated (in the cast) from the cerebellum by a deep fossa. In the Mastodons and Elephants there is the same division of the hemisphere into anterior and posterior lobes by a deep depression (text-fig. 42), but in these later forms the temporal lobes have become greatly enlarged and project much more both ventrally and laterally, while the frontal portions of the hemispheres are more bent down and the olfactory lobes to a great extent lie beneath them. These changes seem to be correlated, at least in part, with the general shortening-up of the skull. The cerebellum [ch.) is comparatively small and narrow from before backvvards ; it is entirely uncovered by the hemispheres. The ventral surface of the brain is not well shown in the cast, but the position of the pituitary body and the bases of the fifth pair of nerves can be made out. Various other details of less importance can be observed, but these need not be referred to fully here, as Dr. Elliott Smith is preparing a memoir on this brain-cast. In the section relating to the Sirenia, some account will be given of the remarkable likeness between the brain now described and that of Eosiren, another piece of evidence of the close relationship of the Sirenia with the Proboscidea. r 106 TERTfARY VERTEBRATA OF THE FAYtTM. (Ippe7' Dentition. — There are three pairs of incisors. The first pair (PI. X. fig. 3, i. 1) are in close contact in the middle line ; they are comparatively small, downwardly directed, prismatic teeth, each implanted in the premaxilla by a long backwardly curved root. Their transverse diameter is roughly ’8 cm. The second incisors (/. 2) form great downwardly directed tusks. Their anterior face is strongly convex, the posterior slightly flattened ; the tooth as a whole is strongly curved and tapers somewhat towards the root, which, in the adult at least, is closed. There is an oblique Text-fig. 41. Cast o£ the cranial cavity of Moeritherium hjonsi: A, from above ; B, from right side. r.h., cerebellum ; f.l., frontal lobe ; inf., pituitary body ; p., pseudosylvian depression ; o.l., olfactory lobe ; t.l., temporal lobe ; V., base of fifth nerve. | nat. size. wear-surface on the posterior side of the crown. No sufficiently well-preserved specimen has been found to show whether the enamel-covering was complete or not. In one skull these tusks project some 4'8 cm. from the jaw, but as their ends arc broken off above the commencement of the wear-surface, it is probable that when complete they protruded at least half as far again ; in this specimen the antcro- M^^RITIIERIUM. 107 posterior diameter of the base of the tusk is about 2‘8 cm., the lateral diameter the same. The third incisor (^. 3) was a small tooth, nearly circular in section, and situated immediately behind the tusk, just internal to its outer angle. This tooth is represented by its alveolus only in all specimens examined ; the antero-posterior Text-fig. 42. Cast of the cranial cavity of Mastodon americanus : A, from above ; B, from right side. ch., cerebellum ; f.l., frontal lobe ; p., pseudosylvian depression ; o.l., olfactory lobe ; t.l., temporal lobe. 108 TEETIARY VERTEBEATA OF THE FAYtM. (liainotcr was about 1'3 cm. The canine (Pi, VIII. fig. 1 a, c.) is also known only from its alveolus, wliicli is situated immediately behind and a little to the inner side of the sock('t of i. o, wliich it resembles both in shape and size. Pehind tlie canine there is a short diastema (about 2'5 cm.). The next tooth, 2 (PI. IX. tig. 4), is roughly triangular in outline with one angle directed forwards. The crown consists of an outer row of cusps and a postero-internal shelf-like projection. The blade consists of two main cusps (a.e., closely united and ])laced somewhat obliquely : of these the anterior (a.e.) is continued inwards as a transverse ridge to the inner border of the crown, where it passes into the cingulum. In front of these main cusps, and forming the anterior angle of the tooth, is a small but prominent cusp, apparently the parastyle (p.s.). Behind the main cusps also there is a small accessory cusp. The postero-internal portion of the tooth forms a broad slightly concave shelf with a raised border formed by the cingulum, which is well developed and crimped along the whole of the inner side of the tooth. The next premolar (^mi. 3) differs mainly from that just described in the presence of a largo antero-internal cusp (deuterocone), which (a.i.), together with the antero- external cusp (a.e.), forms a transverse ridge. The parastyle (p.s.) is present, as also is the posterior accessory cusp. In the specimen figured in PI. IX. fig. 4 the postero-internal shelf is much abraded, the enamel being completely worn through. The last premolar (pm. 4) is similar, but of somewhat smaller size than 3. The molars are bilophodont, each transverse crest consisting of a higher and somewhat pointed outer cusp and a lower, blunter and more worn, inner cusp. The postero-internal cusp has a tendency to be prolonged backwards into a small blunt lobe, which in wear gives rise to the pattern shown in m. I (Pis. VIII. fig. I a, X. fig. 2). This seems to be the beginning of the gradual addition of successive transverse ridges to the posterior end of the tooth so characteristic of the suborder. The cingulum is very well developed on the anterior and internal faces of the teeth. The enamel is marked by a sculpture consisting of numerous irregular grooves : these are especially marked on the cingulum, to which, in some cases, they give a beaded appearance. This sculpture is best developed in the molars of M. gracile, in which also the cingulum is especially well marked (PL XVII. fig. 3). Mandible. — The horizontal rami of the mandible (PI. X. figs. 1, I a) are very stout and massively constructed. Tlie outer face is strongly convex from above downwards, the inner face nearly flat. The spout-like symphysis is long and broad ; its ventral surface is evenly convex from side to side, while the upper surface is concave in the same direction and was continuous anteriorly with the up[)er surface of the procumbent incisors. The mental foramen (m.f.) is situated beneath pm. 3 and somewhat nearer the ventral than the dorsal border. The thickened anterior edge of the very wide ascending ramus arises on the outer side of the jaw about opposite the anterior lobe of m. 3. It slopes somewhat forwards, and from its upper MCERITIIEEIUM. 109 end the superior border runs upwards and backwards at right angles to it, so that the very short coronoid process (cor.) does not rise above the articulation. The condyle itself [cond.) is elongated from within outwards and short from before backwards ; it is convex in both directions and is wider on the outer than on the inner side, which is supported on a flange or buttress of bone arising from the inner face of the ascending ramus. From the condyle the posterior border runs down- wards and backwards in a wide sweeping curve, forming the broadly rounded angular region which projects somewhat below the ventral border of the horizontal ramus. The outer face of the ascending ramus between the thickened anterior border and the buttress which bears the condyle is deeply concave, the bone being very thin. Lower Dentition. — There are two pairs of incisors (PI. X. figs. 1, 1a, i.l,i.2). These teeth are procumbent and directed forwards, their upper surface forming a continuation of the spout-like upper face of the symphysial region of the mandible. The first incisors are much the smaller, and are closely crowded together between the second pair. They seem to have been prismatic teeth with very long crowns and roots ; their transverse width would be about 2’5 cm. The second incisors are a pair of large tusks, which seem to have been more or less triangular in section near the top of the crown, but ovate further down. No well-preserved examples have been found in situ in the jaw, but two specimens which may be regarded as these teeth are here noticed. One of them is a young tooth in which wear has just commenced ; the upper face of its crown is concave from side to side, the inner face flat, while the ventral face is convex and meets the upper face externally in an angle forming the sharp outer edge of the crown, which is chisel-shaped, but thicker internally than at its outer side. The wear-surface is nearly at right angles to the long axis of the tooth ; it is narrow, but as wear proceeded would increase in depth till towards the base of the crown it would be such as is found in the second older tooth referred to below. The crown is covered with enamel, of which the surface is finely sculptured with vermiculate markings below and irregular longitudinal ridges above. The enamel extends much further down the upper and lower faces of the crown than on the sides. In the older tooth the wear-surface is broad, flat, and oval in outline ; it is slightly inclined to the long axis of the tooth, and on the inner and outer sides has already passed below the level of the enamel-covered surface, so that the enamel forms two separate bands, one on the upper, the other on the lower face. The root is very long and slightly curved, with a longitudinal groove on the concave side. At this stage, at any rate, the root was closed. The third incisor, canine, and first premolar are wanting in the mandible. The anterior premolar (PI. IX. figs. 3, 3 a, pm. 2) is comparatively small, and narrow from side to side. It consists of a large main cusp, in front of which there is a small tubercle which may belong to the cingulum. Behind there is a large talon rising in no TERTIAllY VEETEE]IATA OF THE FAYt^M. the middle into a loni^itudinal ridge, such that when the tooth is worn the resulting wear-surface of the main cusp is continued back on this median elevation of the talon. The next tooth (jym.o) is larger and especially wider ; it also consists of a high anterior portion and a posterior talon. The anterior part is composed of three cusps, one of which forms the antero-internal angle of the tooth, while behind this the other two imperfectly separated cusps form a transverse ridge. In wear, the abraded surface of the antero-internal cusp is continuous with that of the outer one of the transverse pair, and this again unites with the surface of the talon, which has a ridge towards its outer side, rising into a tubercle posteriorly. The last premolar (jnw. 4), is wider, and its anterior cusp is less distinctly developed tlian in ])ni. 3. On the other hand, the inner cusp of the transverse pair is much larger and more prominent. The talon also bears a more distinct postero-external cusp. In the third and fourth premolars the cingulum is slightly developed on the outer and posterior sides ; on the latter it forms the raised edge of the talon. The first molar (PI. IX. fig. 2, w. 1) consists essentially of a pair of transverse ridges, each composed of a pair of tubercles and a small talon. The inner tubercles are somewhat higher and sharper than the outer, which are the most worn. There is a tendency to form small tubercles in the valley between the two main ridges, connecting the inner ends of the outer tubercles. The talon consists of a blunt tubercle nearly in the middle line, and a smaller, often obscure, cusp on the inner side. In the third molar (m. 3) the talon is much larger, the main cusp being larger and tending to become subdivided into two, while the inner cusp also is prominent, so that in this tooth the talon forms a third transverse ridge. This third molar is extremely similar to the corresponding tooth in some mandibles of Palwomastodon, while m. 1 and m. 2 differ considerably, owing to the small development of the third lobe ; but at the same time the differences are merely of degree and not of structure. The cingulum is well developed on the outer side of the lower molars. Of the milk-dentition only the last lower milk-molar is known. This is well shown in a portion of the right ramus of a young mandible (text-fig. 43), in which mm. 4 and m. I are well preserved, and beneath the former the crown of jmi. 4 is present. Mm. 4 is much like the permanent molars ; it is bilo])h()dont with a small talon forming the rudiment of a third ridge. Vertebral Column. — The vertebral column of Moeritherium is fairly completely known. In several cases vertebrae have been discovered associated with portions of skulls and teeth that can be definitely determined as belonging to M. hjond ; and in addition to these an almost complete vertebral column has been found associated with a very imperfect skull which is undoubtedly that of a species of Moeritherium, though whether of M. lyotisi or not is uncertain. The vertebrae known to belong to M. lyonai will be described first. In the atlas (PI. XI. fig. 1) the deep cups for the occipital condyles {cond.) in correlation MG-TvITllERIUM. Ill with tlie form of the latter are narrower from side to side than is generally the case, so that the outline of the articnlation with the skull is more nearly circular than usual. The condylar cups are separated above by a slight emargination of the anterior border of the massive neural arch and ventrally by a somewhat smaller emargination of the ventral bar. The neural arch at about the middle of its length is raised into a very prominent transverse ridge, from the anterior border of which smaller and less prominent ridges run outwards and forwards to the upper angles of the condylar cups. Behind the ridge the surface of the arch slopes smoothly down to its concave posterior border. Externally to the outer ends of the above-mentioned Text-fig. 43. Part of right ramus of an immature mandible of Mceritherium lyonsi, showing ym. 4 hi situ beneath mm. 4. f nat. size. lateral ridges the arch is perforated obliquely by the foramen for the first spinal nerve. The transverse processes {t-p.) are rather small and are directed upwards and backwards at their outer ends ; they do not appear to be perforated by the vertebrarterial canal. Anteriorly the base of the transverse process is separated from the neural arch by a notch. The nearly flat surfaces for the axis {a.t.) form an angle of about 45° with the axis of the vertebral column ; dorsally they are widely separated by the neural arch, and ventrally by a much shorter interval occupied by the ventral bar, which is 112 TEETIAliY VEllTEERATA OF THE FATtJM. ])ro(lucc(l l)ackwar(ls in tlie middle line into a blunt hypapophysis and bears on its upper surface a fairly well-defined surface for the odontoid process. In the axis (PI. XI. fig. 2) the neural spine {n.sp.) is high and directed backwards ; its shar]) anterior border is convex and the thickened posterior border bears a deep fossa for tlie attachment of ligaments. The neural canal is high and its floor broad with a median elevation, which is continuous anteriorly with the upper surface of the odontoid. This process (o.rZ.) is relatively large, somewhat laterally compressed, and bears on its ventral surface a well-defined surface for articulation with the atlas. From the hinder border of the odontoid a hsemal ridge runs back along the centrum and deepens and widens considerably posteriorly, so that the hinder articular surface of the centrum is much deeper than broad and is produced downwards into a sort of haemapophysis. 'i’he slightly convex surfaces for articulation with the atlas project laterally beyond tlie rest of the centrum to a considerable extent. Near the posterior border of the centrum there is a small transverse process perforated by the vertebrarterial canal ; the small upper pedicle rises from the base of the neural arch, the larger ventral one from the centrum. The posterior zygapophyses {p.z.) are oval in outline. The rest of the cervical series is not completely known. In the middle cervicals (f 3rd or 4th, PI. XL fig. 3) the centrum is relatively short; its articular ends are slightly concave in the middle, with a broad thickened border ; and the concavity is greatest on the posterior surface. There is a slight Inemal ridge which deepens somewhat behind. The neural spines {n.sp.) are short, pointed, and backwardly directed processes. The large transverse processes are perforated at their base by a canal {v.c.) and are bifid at their extremities, the upper process being very small and directed upwards, the lower forming a large downwardly directed flange. The zygapophyses are very large. The posterior cervical differs from that just noticed in the fact that the spine is higher, while the downwardly directed flange is greatly enlarged and has a thickened ventral border. In the anterior dorsals (PI. XI. fig. 4) the centrum is short, the anterior articular surface is oval and concave in the middle, while the posterior surface is also oval and slightly concave ; externally it passes into a pair of facets {c.f.) for the heads of the ribs. There is a haemal ridge. 44ie transverse processes {t.p.) are short and stout : on their outer ends there is a deeply concave facet {t.f.) looking outwards and downwards for the tubercle of the rib. The neural spine is a high, pointed, and backwardly directed process. A nearly complete vertebral column (C. 10005), associated with a very imperfect skull, was collected from the Middle Eocene beds, and has already been mentioned as undoubtedly belonging to a species oi Mwrithermm, |)ossibly even to a large individual of M. hjoasi. Considering both the size and some differences in details of structure in such vertebrae as can be compared, it seems advisable to refer to this specimen as Mmritlierium sp. until sufficient evidence is available either to justify regarding it as belonging to a new species or definitely relegating it to M. lyonsi. The vertebrae iVKERlTlIEIlIUM. 113 of tins column arc: — the atlas, the last cervical, niueteon thoracic (in this scries there is a gap, one vertebra at least being missing), four luml)ars, and four sacrals. On the whole, the atlas is like that of M. Jjjonsi described above, hut ditfers in several minor points. Thus the transverse s])inous ridge of the neural arcli is wider ; the anterior border of the arch is less concave ; the transverse processes differ slightly in form and are more upturned ; the surfaces for the axis are deeper from above downwards and less extended from side to side. Some of tliese differences may be merely apparent and the result of abrasion or distortion. Ill the last cervical the centrum bears a fairly well-marked hypapophysial ridge ; its articular ends are oval in outline, tlie long axis being transverse, and are slightly concave in the middle. The transverse processes are large, rising partly from the centrum and partly from the arch ; they are stout, and somewhat thickened at the obliquely truncated end. The arch is high and is prolonged upwards into a prominent neural spine. ' There is no trace of an articular surface for the head of the first rib. In the first thoracic vertebra the centrum is of much the same shape as the last cervical, but the broad blunt hypapophysial ridge is almost restricted to the anterior end. The transverse processes are stout and short, terminating in a deeply concave rib-facet, looking downwards and forwards. The anterior edge of the transverse process is produced into a shelf-like projection of bone, which is continuous internally with the anterior edge of the neural arch and bears on its upper surface the broad and fiat anterior zygapophyses. The neural arch is broader than in the last vertebra and the pointed neural spine slopes strongly backwards. There is a slight cup for a rib-head on the upper angle of the anterior face of the centrum, and a much deeper and more sharply defined cup on the upper angle of the posterior face. The second thoracic is closely similar, but the tubercular facet of the transverse process looks directly downwards instead of downwards and forwards. At the same time the anterior shelf-like projection becomes smaller, and there is the first trace of a tuberosity on the upper side of the end of the process, which becomes larger till about the eighth thoracic. In this vertebra, owing to shortening, the transverse process seems to pass into the metapophysis which is largely developed in the following thoracic vertebrae. The following five vertebrae (text-fig. 44) are generally similar, but the transverse processes become shortened and the haemal ridge is wanting. Furthermore, in 4-7 the oval posterior capitular facet {c.f.) becomes very strongly concave and bordered by a prominent rim. In these first seven dorsals the neural spines {n.sp.) are comparatively slender, terminate in a point, and slope strongly backwards. In the eighth dorsal the form of the spine is transitional to the short broad type found in the posterior thoracic region. In this vertebra also the anterior capitular facet is merely a shallow concavity lying beneath and in front of the very short transverse process, which bears a small Q 114 TEKTTAKY VEliTE]?KATA OF THE FAYCM. slifilitly coinex fiicct (/./.) lor the tiihercle of the rib. The posterior ca])itular facets, as in the vertehne in front, are deeply concave and sharply defined. The metapophysial process (?n.) above referred to is large, and in the following two (0 and 10) vertebrae foi'ins a prominent forwardly-projecting point wliicli overhangs the anterior zygapo- physes (a z.). Tlie eleventh thoracic is very similar, but the transverse process merely Anterior dorsal vertebra of Mceritherium : A, from front; E, from left side. a.z., anterior zygapophysis ; f./., capitular facet; m., metapophysis ; neural spine; p.z., posterior zy gapopbysis ; t.f., tubercular facet. | nat. size. Text-fig. 45. Middle dorsal vertebra of MferltJierinm: A, from front; E, from left side. Jjetters as in last figure. .] nat. size. forms a hlnnt ])rominence ; the posterior capitular facet is extremely small, and looks almost directly backwards, while the anterior is more distinct, and forms a shallow concavity hedow and in front of the transverse process. MCKRITJlEIilUM. 115 111 the succeeding- thoracic vcrtehric (text-fig. 45) the head of each rib articulates with one vertebra only, by a dee])ly concave surface {c.f.) situated on the side of the ceutruin iinmediately below and in front of the short blunt transverse process {t.f.), on to the base of which the facet may be continued, at least in 12-13. It is doubtful whether the ribs of this region had any tubercular articulation with the transverse processes. In this region also (12-19) the centrum is considerably wider than high, while the neural s])iue [n.sp.) becomes gradually wider and shorter, and is only slightly inclined backwards. The metapophyses {pi.) form quite prominent pointed processes. The lumbar vertebrie (text-fig. 4G) are four in number. Their centra become still wider in proportion to their height and have a nearly straight upper border. The transverse processes {t.p.) are again large, and arise on a level with the top of the centrum ; in the two posterior lumbars they seem to have been pointed at their extremities. In the form of the neural spine {n.sp.) and the metapophyses (m.) these vertebrae are much like the posterior thoracic. Lumbar vertebra of Mcerltherium : A, from front; B, from right side, transverse process ; other letters as in text-fig. 44. ^ nat. size. The sacrum (text-fig. 47) consists of three fused vertebrae, the centra of which are low and broad, the shape of their articular ends being a transversely elongated oval. The metapophyses, forming prominent forwardly directed processes, are well developed on the anterior zygapophyses {a.z.). The neural spines (n.sp.) are low and broad. The pleurapophyses are broad and stout ; they unite at their outer ends, being separated only by nearly circular interosseous foramina {io.f.). On their fused outer ends they bear a long iliac surface (il.s.) which looks obliquely upwards in front and directly outwards posteriorly. The ventral surface of the sacrum is nearly hat, except near the edges of the iliac surfaces, where it is somewhat deflected. The posterior surface of the last of the fused sacrals is deeply concave. The following vertebra should perhaps q2 IIG TERTLAllY VERTEBRATA OE THE EAYtTM, Text-fig. 47. X a.:., anterior z3^gapoi)Ii}’sis ; io.f., interosseous i'orainen ; il.s., iliae surface ; v.sp., neural spine; j).z., posterior 7,_yga))0])tiy,sis. \ nat. size. MCERITIIEEIUM. 117 be regarded as a free sacral rather than as a caudal. The centrum is depressed, and its ventral face only slightly convex from side to side, ])assing externally into the broad transverse processes. The anterior end of the centrum is convex, and slopes somewhat forwards; the posterior end is much higher in ])roportion to its width: this vertebra is, in fact, intermediate in form between the sacrals and caiidals. These latter are not known in the present specimen, but in another, much less nearly com])lete, column several are preserved. Their centra are laterally compressed, particularly behind, so that while the anterior face of tlie centrum is nearly circular, the posterior is a vertically elongated oval. The neural arch seems to have been confined to the posterior half of the centrum. There are short downwardly directed transverse processes towards the anterior end. Posteriorly the ventral border bears facets for chevrons, which, in some cases at least, were V-shaped. Fore Limb. — The scapiila, the humerus, and the proximal portion of the ulna only are known. No complete specimen of the scajnda has yet been found. The best example (from the left side) is figured in PI. XI. fig. 5. The glenoid cavity {g.c.) is oval in outline, and the articular surface is continued forwards on to the posterior surface of the large and prominent coracoid process (c.). Anteriorly this process bears a rough ridge, which passes above into the coracoid border (c.b.). This border is concave below, but is incomplete above ; it seems, however, to have curved forwards so that the upper part of the blade was wide. The glenoid border (g.b.) is gently curved backwards; the suprascapular region is broken away. The spine (s.) originates about 2‘5 cm. from the glenoid cavity; it forms a prominent backwardly inclined flange, parallel with the glenoid border ; it cannot be seen whether or not there was an acromion. The postscapular fossa is narrow but deep, and overhung by the spine ; the prescapular fossa is wider and more open. This scapula, in the backward sweep of its blade, presents some approach to the Sirenian type, and in the large size of the coracoid process and the form of its coracoid border is similar to the scapula of Barytherium described below. In the humerus (PI. XI. fig. 6) the head (h.) projects strongly backwards and inwards ; it is much more strongly convex from before backwards than from side to side. The greater tuberosity is large and rises to about the same level as the head. Externally it is flattened, internally it forms the outer border of a broad bicipital groove, the inner side of which is formed by the small but still well-defined lesser tuberosity. The shaft is chiefly remarkable for its extreme lateral compression. The narrow flat anterior surface is continuous above with the flattened face of the greater tuberosity ; lower down it passes into the inner face of the bone, its prominent outer border forming the deltoid crest [d.], from which a rounded ridge runs obliquely across the anterior face of the bone to the inner end of the distal articular surface, so that the whole bone when seen from the front appears to have a slight spiral twist. The inner condyle {i.c.) is very large and projects below the rest of the bone; it is not perforated by an entepicondylar 118 TERTJAEY YERTEBRATA OF THE FAYCM. foriuiK'ii, but tliere is a doc]) fossa lying between the condyle and the olecranon fossa (o.f.), wbicb also is veuy dee]). 'I’be outer condyle is coin])aratively small; from it the edge of the boM(' is continued u]) as a narrow backwardly directed flange, which dies away just below tlu' middle of tbe shaft; distally this ridge forms the outer border of the olecranon fossa, and higlmr np the sharp outer border of the expanded distal end of the bone, wbicb above the olecranon fossa is strongly concave from side to side. Tbe edge also is in j^art the ecjuivalcnt of the supinator ridge, and the large development of this and of the inner condyle indicates that the limb was ca])able of extensive movements of ]>ronation and su])ination not found in the more specialised Ungulates. The distal articulation is divided into an outer and an inner lobe by a shallow dc])ression ; above the outer trochlea the front of the bone is occupied by a well- marked coronoid fossa (c.f.). The ])roximalend only of the ulna is known (PI. XI. fg. 7). The olecranon process (ol.) is large, thickened at the extremity, and rises high above the articidatiou ; it is not directed backwards to any great extent, but merely continues u})wards the long axis of the shaft. The sigmoid notch is dee])ly concave, the up])cr part of the articulation being considerably prolonged forwards. The lower ])()rtion of the humeral surface is deeply bilobate ; the radius seems to have been in contact with the outer lobe only. Beneath the articulation on the anterior face of the bone towards the outer side there is a deep depression (r.) for the radius. I/ind JAnih. — The (PI. XI. figs. 9, 9 A; text-fig. G8, ])) differs widely from that of the later Proboscidca, owing mainly to the narrowness of the ilium. The crista itii (c.i.) is short and almost at right angles to the sacral and acetabular borders, which are ])arallel with one another. The outer angle of the crista forms a blunt projection. Tlie sacral surface is very long, extending over the anterior three- fourths of the sacral border ; it is gently convex from above downwards, and from its position and antero-])osterior extent it shows that the long axis of the ilium is nearly parallel with that of tlie vertebral column. The acetabular border is gently concave in its anterior two-thirds ; posteriorly it seems to divide on either side a strongly marked pit for the rectus femoris muscle) lying immediately above and in front of the rim of the acetabulnm. The gluteal surface is slightly concave from side to side ; the ])elvic (inner) surface is nearly flat. On the ventro-internal face of the ilium is a ])romincnce (ileo-pectineal), from which there runs back a ridge continuous with the anterior border of the ]uibis (^i/n). 'Plie acctalndum (a.) is horseshoe-shaped, the very ])romincnt raised rim Ix'ing iuterru])ted ])ostero-inferiorly by a wide notcli, which leads into the large ])it for the ligament, and opens externally on the surface of the ischium, 'llio j/uhis is for the most ])art broken away in all tbe sjiecimens examined : this sc'cms to be the consecjuencc of the slendei uess of the free portion of this bone. 'I'he ischiuni (/.s.) is much stouter and MCERITIIEKIUM. 119 continues back the long' nxis of the ilium. Where this hone forms the outer houndary of the obturator foramen it is trihedral, hut ])osteriorly it flattens out into a broad and comparatively thin plate, of which the upper outer angle {tuber ischit) is very prominent [is.t.). The posterior border is somewhat convex. Internally the hone is produced into a process forming the posterior boundary of the obturator foramen, and so thin that in no specimen does it remain unbroken, so that nothing is known as to the form and extent of the symphysis. The peculiar interest of this pelvis lies in its great resemblance to that recently figured by Abel * as belonging to the Sirenian, Eotheriimi mgyptiaeum, Owen (text-fig. 68, C), a species occurring in the somewhat earlier white limestone of the Mokattam Hills. In this pelvis there is the same straight and narrow ilium, the same greatly expanded ischium, and an acetabulum of almost exactly similar form. Unfortunately, in no specimen of the pelvis of Meeritlierium is the pubis well preserved, hut it w^as clearly comparatively thin and w'eak. The chief differences between the two pelves seem to be : (1) so far as can be ascertained from Abel’s figure and description, the sacral surface is less distinctly developed in Eotheriuin ; (2) the position of the fossa for the attachment of the rectus femoris muscle is a little different ; (3) the obturator foramen is rounder in Eotherium. Nevertheless, the similarity of the two pelves is such that if that described by Abel is without doubt Sirenian (and it seems highly improbable that it is anything else), then it may fairly be suggested that Moeritherium and Eotherium, both occurring in the same region (the one the most primitive Proboscidean, the other occupying the same position with regard to the Sirenia), are in fact closely related, and had a common ancestor in early Tertiary times, -probably in the Lower Eocene. It is interesting to note that the acetabulum of Eotherium indicates the presence of a lai'ge functional femur, so that the animal must have been less exclusively aquatic than the later Sirenia. Furthermore, in the rather later beds in which the remains of Moeritherium are found there is a Sirenian Eosiren, in which the pelvis (text-fig. 68, B) is already almost as much reduced as in the later Ilalitherium (text-fig. 68, A); the adoption of a completely aquatic life having apparently led to a very rapid reduction of the pelvis and hind limb through disuse, wliile the terrestrial, probably swamp-loving, Moeritherium retains the more primitive type of pelvis, which, by the widening of tlie gluteal and pelvic surfaces, and the consequent lengthening of the crista ilii, became the broad pelvis of the larger Proboscideans. The head of the femur (PI. XL fig. 8, h.) is large, rounded, and pedirnculate ; its posterior surface bears a deep pit for the ligamentum teres {l.t.)', it is separated * O. Abel, “ Die Sirenen der mediterrauen Tertiiirbildungen Oesterreichs,” Abbaudluagen der k.-k. geologiscbeu lieichsanstalt, vol. xis. pt. 2, pi. vii. fig. 1 (Vienna, 1904). 120 TERTIARY VERTEBRATA OF TILE FAYCAM. from tlu' ^roiit trocliantc'r wltich rises slightly above it, by a shallow rounded notch. 'I'lie lesser trochanter {l.tr.) is a very ])rominent ridge of bone forming the inmn’ border of tlu' large digital fossa. From the most prominent point of the inner trochanter a slight ridge runs obliquely to the base of the great trochanter, dividing the fossa into an n])])er and lower section. The middle portion of the shaft is roughly triangular in section, the outer angle forming a roughened ridge, which is the only rejn-esentative of the third trochanter. Below this point the shaft is oval in section, the flattening being antero-]>osterior. The trochlear surface is small, and the ridge forming its outer border somewhat the more prominent. Both condyles are small ; the outer is somewhat the larger, though at the same time the inner projects a little beyond it. Posteriorly tiie condyles are separated by a deep and narrow intercondylar fossa. The posterior surface of the shaft immediately above the condyles is slightly concave from side to side. In its straightness, in the relatively small size of its articular ends, and in the absence of an inner trochanter, this femur is not unlike that of the later Proboscidea ; and while the presence of a depression for the insertion of the ligamentum teres is a point of difference between it and most of the later members of the group, a deep and similarly situated pit occurs on the head of the femur of Pala’omastodo/i. Moeritlierium lyonsi, Andrews. [Plates VIII.-XI. ; text-figs. 40-47.] 1901. MoerilJierinm t W. Andrew.s, Tagel)latt dcs V. Internationalcn Zoologen-Pongrosses (h W. Andrews, Phil. Trans, vnl. 19(1 n, pp. 113-117, figs. (1. W. Andrews, th'ol. IMag. [5J vol. i. pp. 109-112, Hg. 1. 1903. 1 901. Type Specimen. — Mandible associated with up])er molars and a dorsal vertel)ra (PI. X. figs. 1, 1a): Geological Museum, Caii-o. The ty])e s])ecies, iii which the length of the mandible is about 32 cm., and that of the molar and ])remolar series 17’2 cm. Form. (T Loc. — Qasr-el-Sagha beds (Middle Eocene) and Fluvio-marine beds (U])per Eocene) : north of Birket-el-Qurun. C. iOOOO. Upper molars, inandil)le, and a dorsal vert(d)ra. The mamlihlo is the type of the spec-ies de.scrihed in llie ‘ Tagchhitt des V. Internationalen Zoologen-Congres.ses,Ai<). (I, p. 1 (Beilin, 1901) ; also dc-scrihed and figured in Geol. Mag. [4] vol. viii. (1901) pj). 103-5, MCKHITIIERIUM LYONS!. J2l lio'. 2 c ; iilso 1*1. X. fiii. 1. Tlio v(‘rtel)r;i i.s fiotired on 1*1. XI. fip'. 4. Middle Kocene. o ' o “ The diiiien.sions (in centimetres) oi' the inandihle and lower teeth are : — Total length 32 Height of condyle above inferior border 15'3 Length of molar and prcniolar .scales 17'2 Length. Width. pm.2 2-2 1-6 pm/i 2-3 2-1 prn. 4 2‘o 2‘3 m. 1 2-65 2-45 m. 2 3'5 3 m. 3 4-2 3 M. 8146. C. 7867. Made in the British Mu seam. I’laster cast of the above specimen. Nearly complete skull of a young individual In which the second incisor and last molar are not yet cut. The description of the skull given in this volume is founded mainly upon this specimen, which is figured on PI. VIII. and PI. IX. fig. 1. Upper Eocene. The approximate dimensions (in centimetres) of this skull are Greatest length from end of condyles to tip of snout ... 35 Length from hinder border of palate to tip of snout .... 21 „ summit of occiput to tip of snout 32 Greatest width at zygomatic processes of squamosal .... 22'7 „ of occipital surface 17'4 „ of supraoccipital escutcheon 9-7 Height of occipital surface above /omwm magnum .... 8‘7 Width between outer angles of condyles 9‘3 ,, of sknll-roof at temporal fossa 6 „ „ orbits 6'6 „ of glenoid surface 7 3 ,, of palate between m.\ 3'3 „ of foramen magnum 4'2 Length of premolar series 7'3 The dimensions (in centimetres) of the teeth are : — Length. Width. prn. 2 2‘7 ' 2 pm. 3 2’5 2'8 pm. 4 2'1 2'8 m. 1 3 2-6 m. 2 3-2 2-9 M. 8875. Plaster cast of the above specimen. Made in the Bntish Maseuni. M. 9225. Skull, very slightly crushed and nearly complete, with the exception of the zygomatic arches : the nasals are well preserved and terminate anteriorly in points which overhang the narial opening. The vertical plates of the pterygoids are thick and appear to have a descending plate of the alisphenoid fused on their outer face ; there is an alisphenoid canal opening anteriorly into a groove running upwards and forw’ards, as in Palceo- K 11^2 TERTIARY VERTKRRATA OF THE FAYtJAI. Didst odofl. J^joeono. Tlic ieoth are for tlio most part represented by their bases only. Tlie dimensions (in centimetres) of this specimen are : — Mid.lle Greatest length from end of condyles to tip of snout ... 37 Length from hinder border of palate to tip of snout ... 23 „ summit of occiput to tip of snout 34-7 Greatest width of occipital surface 15-5 Height of occipital surface above ybra?neft magiuim .... 7'5 Width of skull-roof at temporal fossae 6'5app. Length of molar and ju-emolar series 15’2 ,, premolar series 6‘7 molar series 8’5 Presented Inj Baron Franz JVopcsa, 130.3. C. 10002. J’ortions of large skull. Described and figured in Geol. Mag. [4] vol. viii. (1901) p. 404, figs. 2 A, 2 B; also PI. X. figs. .3,4 Middle Eocene. The dimensions (in centimetres) of this specimen are : — Greatest width at zygomatic processes 27 „ of occipital surface 19'4 Height of occipital surface above /orumra .... 7'7 Width between orbits 6’5 Length of broken tusk (h 2) 4‘6-p Width of broken tusk {i. 2), side to side 2-8 „ „ before backwards 2-8 Length of premolar series 6’8 app. M. 8192. Plaster casts of the above specimen. Made in the British 2[i(seinD. M. 8905. Portion of skull, including the right maxilla. Middle Eocene. resented In/ the Kiji/ption Government, 1904. M. 8904. Anterior portion of skull, showing the sockets of the incisors. Middle Eocene. Presented Inj the Egyptian Government , 1904. M. 8906. Imperfect skull, teeth not preserved. The length from the summit of the occiput to the tip of the snout is 32 cm., that from the hinder border of the palate to the same point about 21’,5 cm. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 8884. Palatal region of skull with molars and premolars. Upjior Eocene. The dimensions (in centimetres) are : — Length of premolar series 7 Width of palate op[)0»ite m. 1 . . . . I3*(> tienf!;lli. Width. .... 25 2 .... 2-.5 2-8 pm. 4 2-7 .... 2-9 2-5 .... 3-3 2-8 J‘ resented hy the Egyptian Government , 1901. C. 8847. 1 *ortion of the palatal region of the skull with pni. 3, pm. 4, ni. 1, and m. 2 well preservcui on the right side. The base of the zygomatic process of the maxilla is over the promolars. Ujiper Eocene. The dimensions (in centimetres) are : — ]\1(1‘:ritiiei{ium lyoxsi. 12B M. 8898. M. 9116. M. 9117. C. 8831. C. 8832. C. 7910. M. 8500. C. 10001. M. 8147. C. 8112. M. 8907. Longtli of m. 2 .j’2 „ m.l 2-!) ,, pm. ‘i 2'6 Posterior ])ortIoii of sktill from wliieli the cast of tlio hruiii-case M. 911G was made. IMiddle Eocene. Cast of cranial cavity of last .specimen (text-fig. 41). Made in the British ^^^lsenm. Plaster cast of the cranial cavity of the imperfect skull C. 10002. Made in the British Museum- (?) IMuch-wmrn low'er tusk (second incisor), .showing the wear-surface truncating the summit nearly at right angles and the very long but closed root, grooved above. Total length 13 cm. ; width of crown 2 8. Upper Eocene. (?) Crowm of a similar but much less worn tooth. The crown is covered with a thick enamel which extends furthest down on the upper and lower faces ; wear-surface at present a narrow band at right angles to long axis. Width of crown 2 cm. Upper Eocene. (?) Upper tusk (second incisor), greatly curved ; root closed ; wear-surface on posterior side of crown. Length in straight line 12‘5 cm.; width of crown 2‘G cm. Upper Eocene. Right upper premolars and m. 1 of a large individual. The size of the teeth is somewhat exaggerated by the cracking and slight displacement of the enamel (not showm in figure). The premolars are figured in PL IX. fig. 4. Upper Eocene. The dimensions (in centimetres) of the teeth are : — Length. Width. pm. 2 2‘6 2’2 pm. 3 2‘6 3’2 p??i.4 2‘2 2'9 m.l 3T 2-7 Length of the preniolar .series 7’y. Bresented by IP. E. de Winton, Esq., 1903. Upper molars and premolars found close to type. Described and figured in Gleol. Mag. [4] vol. viii. (1901) p. 404, fig. 2 a ; also PI. X. fig. 2. Middle Eocene. The dimensions (in centimetres) of these teeth are : — Length. Width. p)m. 2 .... 2-7 2-3 app. pm. 3 .... 2-65 2-95 pm. 4 .... 2-3 2-75 m.l .... 29 2-7 m. 2 .... 2-6(?) 2-35 Plaster cast of the above specimen. Made in the British Mvseum. Right upper premolar. Upper Eocene. Portions of upper and lower jaws with imperfect teeth, axis, and two other cervical vertebrae, some imperfect dorsals, and a fragment of a pelvis. Middle Eocene. Presented by the Eyyptian Go-verrinienty 1904. R 2 124 TERTIAKY VERTERIiATA OV THE FAYOAr. M. 9114. M. 8902. C. 8808. M. 8885. M. 8898. M. 8894. M. 8901. M. 8895. C. 8127. C. 7838. M. 9233. Two posterioi lol'l upper luohirs. Middle Koeciie. The dimensions (in cenl iinelres) of (lie.sc teeth :ire : — Lengtli. Width. m.2 ,‘3 2-8 m. ;5 3-2 2’8 'r!nry the Egyptian Government, 1904. Nearly complete mandible, incisors and pm. 2 broken away. Upper Eocene. The dimensions (in centimetres) of this specimen aia* : — Total length (not including incisors) 32-8 Horizontal width of ascending raimis 1G'.5 JiCngth of molar series O-!) „ premolar series 7T Anterior portion of mandible, showing symphysis and right ramus witli pm. 3-4 and m. 1-2. Upper Eocene. The dimensions (in centimetres) of this specimen are ; — Length of symphysis pmi. 3 pm. 4 m. 1 m. 2 Length. 2-8 2-.') 2-8 3-4 9'u app. Width. 1-8 2T 2-1 2-7 Presented by the Egyptian Government, 1901. Portion of mandible. Middle Eocene. Presented by the Egyptian Government, 1904- Portions of mandibles. Middle Eocene. Presented by the Egyptian Government , 1904. Portion of left ramus of mandible with premolars. Middle Eocene. Presented by the Egyptian Government , 1904. Fragment of skull and anterior portion of mandible with much weathered incisors. Middle Eocene. Presented by the Egyptian Government, 1904. Portion of right ramus of mandible with pm. 2-4 in perfect jireservation. Figured on PI. IX. fig. 3. Up])er Eocene. The dimensions (in centimetres) of the tetdh tire: — Length. Widtli. pm. 2 2-3 1-1 pnn. 3 2'0 1-7 pnn. 4 2'4 2 Length of premolar series 7. J’osterior portion of the left ramus of the mandible, showing the last milh-molar with the germ of 7>m. 4 beneath it ; nt. 1 is just in w ear. M. 2 and m. 3 are represented by the alveoli onl}^ and probabl}" ?«.. 3 had not yet emerged (text-fig. 43). Ujiper Eocene. The dimensions (in centimetres) of the teeth are : — Length. Width. wm. 4 2-G 1-8 pm. 4 2-2 m. 1 2-7 2-1 Plaster cast of tlie above siiecimen. Made in the Hritish M nsm m . 3KERIT11KRI UM LYONS!. 125 C. 8832. Crown of second lower incisor. C. 8801. Worn second lower incisor. M. 8501. Right and left lower molars and jjremolars in nearly perfect ])reservation. The teeth of the right side are figured on PI. IX. fig. 2. Upper Eocene. The dimensions (in centimetres) of the teeth are : — Length. Width. pm. 2 2-0 1-4 pm. 3 2’7 1’9 pm. 4 2’4 2T m. 1 3 2-2 m. 2 3-2 2-G 7>i. 3 4 2’8 Length of preniolar series 7'3. Length of molar series 9’9. Presented hy W. E. de [\lnlon. Esq., 1903. M. 9118. Lower molars and premolars. Middle Eocene. M. 8900. Portions of upper and lower dentition greatly worn. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 8914. Skull and vertebral column, incomplete and badly preserved. Presented hy the Egyptian Government, 1904. M. 8909. Atlas vertebra. Figured PI. XI. fig. 1. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 8909 a. Atlas vertebra. Middle Eocene. Presented hy the Egyptian Government, 1904. C. 9073. Atlas vertebra. Upper Eocene. C. 10059. Axis vertebra. Figured PI. XI. fig. 2. Middle Eocene. M. 8915. Three imperfect axis vertebrae. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 8899. Cervical vertebra and fragments of skull. Vertebra figured PI. XI. fig. 3. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 9227. Imperfect cervical vertebra. Middle Eocene. Presented hy Baron Franz Nopcsa, 190;>. M. 8903. Two imperfect dorsal vertebrae. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 8908. Two imperfect dorsal vertebrae. Middle Eocene. Presented hy the Egyptian (rovemiment, 1904. M. 8921. Imperfect dorsal vertebrae. Middle Eocene. Presented hy the Egyptian Government, 1904. M. 9226. Dorsal vertebrae. Middle Eocene. Presented by Baron Franz Nopcsa, 190.1. M. 9228. Dorsal vertebra. Upper Eocene. Presented hy Baron Franz Nopcsa, 190.1. M. 8917. Dorsal and sacral vertebrae, much weathered. Middle Eocene. Presented hy the Egyptian Government, 1904. C. 10053. Lumbar vertebra. Middle Eocene. C. 10035. Imperfect sacrum. Middle Eocene. TEirriAKY YEinp:i}llATA OF THE FATtjM. 12(; C. 10020. Dorsal v('rtol)ra', scajjula (1*1. XI. fig. 5), portions of fi'inur, and pidvis. Middle Eocene. The (liinensioiis (in centimetres) ot‘ the scajnda so far as jireserved are: — Lengfli from coracoid process to postero-superior angle . . 21 „ of glenoid surface in straight line 5-8 AVidtli of glenoid surface in straiglit line 4 M. 8918. Fragments of scajnihe. IMiddle Eocene. Presented hji the E(j)jpt'ia)i (jovernment , 1901. C. 7962-3. Pair of well-preserved humeri. Upper Eocene. The dimensions (in centimetres) are : — Length 26 Width of head 4'2 Antero-posterior width at deltoid crest 5'2 AVTdth of distal articular surface 4'5 „ distal end at condyles 7'6 M. 8910. P ortions of two humeri. Middle Eocene. Presented Inj the Kijyptian Government , 1901. K. 8916, M. 9115. Imperfect humeri. Middle Eocene. M. 8861. Distal portion of humerus. Uj)per Eocene. Presented Inj the E(fj/ptian Government, 1901. M. 8931. Left humerus. Figured PI. XI. fig. G. Aliddle Eocene. The dimensions (in centi- metres) of this s])ecimen are : — Length 24 Autero-posterior width at deltoid crest 5 Lateral width at same point 2‘4 "Width of distal articular surface 4-6 „ distal end at condyles 7’2 Presented h)j the Eijijptian Government, 1904. M. 8911. Pro.ximal end of ulna. Figured PI. XI. fig. 7. Middle Eocene. M. 8911a. Proximal ends of two ulnte. Middle Eocene. M. 8920. Portions of ])elves. Middle Eocene. M. 8932. Ilight femur. Figured PI. XI. fig. 8. Middle Eocene. The dimensions (in centi- metres) of this specimen are : — Length 27 Width of proximal end < ’O Diameter of head 3-5 M'^idth of middle of shaft 3’3 „ distal end 3'2 C. 10004. Left femur. Middle Eocene. The a[»[)roximate dimensions (in centimetres) are : — Length 26-8 Width of proximal end 7 Diameter of head 3'5 IVddth of middle of shall 3'2 „ distal end M. 8920 a. Up[)or end of tibia. Middle Eoceiun ]\I(KKIT1IKIUIJM GRACILE. 127 Moeritherium gracile, Andrews. [Plate XVir. figs. 1-3.] l'.)02. Ma’vitheriuin (jrac'de, C. W. Andrews, Geol. Mag. [4] vol. ix. p. 292. Type Speeimen. — An imperfect skull (PI. XVII. figs. 1, 2), including the palatal region, associated with cervical, dorsal, and lumbar vertebrae ; Geological Museum, Cairo. I'his species is distinguished from M. lyonsi by its comparative lightness of structure, the narrowness of the palate, the smaller size of the upper molars and premolars, particularly of m. 3, the strong development of the cingulum in these teeth, and by the considerable inflation of the cranial region of the squamosal, which apparently contains extensive air-sinuses. Form. & Log. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. C. 10003. Cranial and palatal regions of skull with some vertebras. Type specimen described in Geol. Mag. [4] vol. ix. p. 292. Figured on PL XVII. figs. 1, 2. The palatal portion (fig. 1) shows very well the great enlargement of i. 2, the extension forwards of the maxilla (»ur.) beneath the premaxilla (ptux.), the presence of a median anterior palatine vacuity, the relatively small size of the teeth, particularly of the third molar (m. 3). The cranial region (fig. 2) shows the comparative narrowness of the supraoccipital escutcheon (soc.) (cf. PI. X. fig. 4 a) and the inflation of the upper part of the stpiamo.sal (sq.). The dimensions (in centimetres) of this specimen are : — Distance from anterior end of snout to hinder border of palate . 21 Width of palate o^^posite 2 2'8 Approximate width of supraoccipital escutcheou 8‘G Total width of occipital surface 18‘6 The dimensions of the teeth are : — Length. Width. 2^m. 2 2-2 1-8 2)m. 3 2 2'3 2ml. 4 2 2-1 (?) m. 1 2-3 2-3 7)1. 2 2'4 2’5 m. 3 2-8 2-4 Length of molar and premolar series 13-7. Length of molar series 7'5. Length of premolar series 6’2. The vertebrae belonging to this skull include the centra of the axis and the five posterior cervicals (two having part of the arch preserved), an anterior dorsal with part of the arch, also five other dorsal and two lumbar centra. The form of the axis, so far as it is preserved, is similar to that of the axis of 4/. hjonsi. The centra of the posterior cervicals are oval in outline and slightly 128 'lEIiTlAIiY VEKTEP.IiATA OF THE EAYCM. concave at hotli ends, Tlie transverse })rocesses oE all exce[)t the seventh are perEorated by a vertebrarterial canal, and on the anterior ones there is a strong hypapophysial ridge on the hinder end oE the centrum. The anterior dorsal has an oval biconcave centrum ; the external angles oE the posterior Eace bear concave facets Eor the capitulum of the rib ; the transverse process is stout and short and bears a large do'vvnvvardh^- directed tubercular facet, strongly concave from before backwards. The other dorsal centra have a straijxht neural border and are strongly convex below. The lumbar centra are similar, and bear on their sides strong flattened transverse ju’ocesses. Height of W id til of Length of anterior face. rfilto. centrum. Atlas 7'o 6-5 (with odontoid). Last cervical . . . . . . . 3-3 3-.5 2-6 Anterior dorsal . . . 3-3 3-8 2-8 Postei'ior dor.sal . . . . 3-8 Po app. 3-8 Lumbar . . . 3-8 4-7 3-8 II. 8191. Plaster cast of palatal region of type skull. Made in the British Museum. M. 8912. Left upper molars. Figured on PI. XVII. fig. 3. These teeth show the well-developed cingulum and the peculiar sculpturing of the enamel. The dimensions (in centimetresj are : — Length. Width. 2-5 2-1 ))U 2-7 2-3 m. •> 2-,S 2-5 I’re.senfeil Inj the Egyptian Government, 190-1. il. 9229. Centrum oE axi-; with odontoid. Presented hy Baron Franz Xopesa, 1905. Moeritherium trigonodon, Andrews. [Plate IX. fig. 5.] 1901. .]f(rritherium irigodon, (h W. Andrews, Gcol. IMag. [5] vnl. i. |i. 112. Type Specimen. — I’osterior portion of right ramus of mandible (PI. IX. fig. 5) ; British Museum. This species is distinguished hy the form of the posterior lower molar, which narrows j)osteriorly, the talon consisting almost entirely of one large tubercle ; also by the rapidity with which the teeth decrease in size from behind forwards. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of P>irkct-el-Quruu. MCERITIIEEIUM TEIGONODON. 129 M. 8499. Posterior portion of right ramus of mandible with tlie molars. Ty[)e specimen described in Geol. Mag. [.5] vol. i. p. 112. Figured PI. IX. fig. 5. The characters of the teeth are as follows : — M. 1 is a bilophodont tooth with a small posterior lobe ; each transverse crest consists of two tubercles. Most of the outer half of the tooth is wanting ; the inner half consists of a high anterior cusp and a somewhat lower posterior one, separated by a deep valley. M. 2 also wants a great part of its inner half. It is similar to m. 1 exce])t that there is a posterior lobe consisting of a large blunt tubercle, which lies immediately behind the outer tubercle of the posterior crest. These two teeth are much like the corresponding ones of M. lyonsi ; but m. 1 is smaller in proportion to m. 2, and similarly rn. 2 is smaller in proportion to m. 3. M. 3 is quite unworn ; it differs considerably from m. 3 of M. lyonsi. Like the other molars, it consists of two transverse ridges with a talon. The transverse ridges are placed somewhat obliquely ; the anterior one consists of a high pointed outer tubercle and an inner one which is partially divided into two. In the posterior crest the outer half again consists of a high pointed tubercle, but the inner half here consists of two subequal tubercles. The talon is composed of a large tubercle lying in the same line as the outer tubercles of the crests, and on its inner side there are several small tubercles ; on its outer side the cingulum is well developed. The talon as a whole is triangular in outline, its posterior angle being on the outer side of the tooth. In M. lyonsi (PL IX. fig. 2 ; PI. X. fig. 1), on the other hand, the talon is much wider and consists of an outer and inner tubercle which form a broad crest, thus converting the tooth into a trilophodont one. This difference in the talons appears to justify the separation of the present form as a distinct species at least, and not improbably further material will show that a new genus must be established. The enamel of the whole tooth is raised into irregular ridges and small tuberosities. The dimensions (in centimetres) of the teeth are : — Length. Width. m. 1 2-6 ? m. 2 3-2 ? TO. 3 4 2'4 The length of the molar series is 9-8 crn. Moeritherium sp. C. 10005. Nearly complete vertebral column with very imperfect skull. Vertebrte described above (pp. 112-117), and some of them figured (text-figs. 44-47). This specimen may be merely a large individual of M. lyonsi. Middle Eocene. S 130 TERTIARY VERTEBRATA OF THE FAYtM. Family PAL^OMASTODONTID.E. In the skull the nasals shortened and the external nares somewhat shifted back from the end of the snout. Mandible with elongated spout-like symphysis, projecting beyond the skull. A single pair of large incisors (^. 2) in both upper and lower jaws. Upper incisors in form of downwardly-directed tusks, with a band of enamel on their outer side ; lower incisors procumbent and continuing forwards the upper surface of the spout-like symphysis. Premolars replacing milk-molars in both upper and lower jaws ; molars with not less than three transverse ridges. This family includes the Eocene genus PaUeoinastodon and the Miocene Tetrahelodon, possibly also the problematical Phiomia. The species range in size from little larger than Mceritherium to nearly as large as the existing Indian Elephant. Genus PAL.fflOMASTODON, Andrews. [Tageblatt des V. Interna tionalen Zoologen-Congresses, No. G, p. 4, Berlin, 1901 (Verhaiullungen, }>. 528, 1902).] Skull with sagittal crest ; nares just in front of orbit. Dental formula : — /. ; c. ; 'inn. | ; m. ^ . Last premolar bilophodont ; molars trilophodont. Neck more elongated than in Plephas] limb-bones, so far as known, much like those of the later Proboscidea. This genus is at present known only from the Upper Eocene Fluvio-marine beds of the Fayiim, where it is represented by several species, the type being Palceomastodon beadnelli. The several species are distinguished by (1) difference of size ; (2) the form of the symphysis and its position with regard to the anterior ])remolars ; (3) the degree of development in the last lower molar; (4) the degree of development of secondary tubercles in the molars. The Skull (Pis. NIL, XIII. ; text-figs. 48, 49 A). — Though differing widely in general appearance and in many details from that of the later Elephants, the skull is nevertheless typically Proboscidean in all essential points of structure, and may be described in short as that of a very dolichocephalic Elephant. Some of the more obvious differences between it and the skull oi FAephas are : — (1) the relatively small though still considerable development of the bone cells and sinuses in tlie upper and hinder region of the cranium ; (2) in correlation witli the last character the presence of a sagittal crest, which extends to a point about over the middle of the temporal fossa, where it divides into two supratemi)oral ridges, which run forwards and outwards and probably terminated in the postorbital ])rocesses of the frontal; (3) the elongation of the hauls cranli and })articularly also of the palatal region, PA LA^OMASTOUON. 131 tliis latter, of course, being connected with the persistence tlirough life of most of the molar and premolar series (viz.,2>?^- 2, 3, 4, and m. 1, 2, 3), which are brachyodont and exhibit the mode of succession common in the more generalised Ungulates. Other points will be referred to in the detailed account of the structure of the skull. The specimen now described (PI. XII. ; text-figs. 48, 49 A) is fully adult, the last Text-fig. 48. Semi-diagrammatic figure of the skull and mandible of Palceomastodon : A, skull from above ; B, skull and mandible from side. ant.orh., antorbital foramina ; e.a.m., external auditory meatus exo., exoccipital ; /r., frontal ; ju., jugal ; lac., lachrymal ; l.i., lower incisor ; mx,, maxilla ; n., nasal ; nar., external nares ; pa., parietal ; par., paroccipital process ; premaxilla ; s.oe., supraoccipital ; sq., squamosal; u.i., upper incisor. About ^ nat. size. molar being already considerably worn, and the sutures in some cases closed, so that it is difficult or impossible to determine their position. The basioccipital (text-fig. 49 A, boc.) is fused with the exoccipitals, so that its exact limits cannot be made out. It is deeply notched behind by the lower border of the foramen magnum, and probably formed a small part of the inner ends of the occipital s 2 132 TEETIARY VEETEBRATA OF THE FAYCm. condyles. Its body is keeled ventrally and it unites with the basisphenoid at about tlie level of the ghuioid cavity for the mandible : the line of union with the hasi~ sphenoid {i>sp.) is marked by a fairly prominent transverse ridge. The lateral border of the median limb is separated from the anterior border of the lateral portion by a sharp notch, through which the hypoglossal nerve probably passed, there being, as in the later Troboscidea, no condylar foramen. With tlie possible exception of a small portion of their inner ends, the whole of the occipital condyles are formed by the exoccijntals [exo.). The condyles themselves are much larger and project fuVther behind the skull than in Elephas, in which their articular surface seems to look mainly downwards and to project very little beyond the rest of the exoccipital bones. Here, on the other hand, the condyles are so sharply marked off from the rest of the bone as to be almost pedunculate. Their articular surface extends far on to the dorsal surface, and they are very strongly convex from above downwards — in fact, roughly speaking, they may be said to form about two-thirds of tlie surface of a cylinder — and at the same time they are slightly convex from side to side. From the form of the condyles, therefore, it would appear that the range of movement allowed to the skull in an up-and-down direction must have been very great, while that from side to side was comparatively restricted. The foramen magnum {f.m.) is oval in outline and does not look downwards so much as in Elephas, mainly owing to the fact that the posterior border of the basi- occipital is less deeply notched. Ventrally and laterally the surface of the exoccipitals runs forwards in a gentle curve to join the post-tympanic flange {ptp.) of the squamosal. On the ventral surface near the union with the squamosal the exoccipital bears a blunt prominence {pp.), which is the only representative of the paroccipital process, and is therefore homologous with the thin plate-like ventral process of the bone described in the skull of Mceritherium. The upper portion of the bone above the condyles and the foramen magnum slopes forwards, and the two elements meet in the middle line, separating the supraoccipital from the foramen magnum by a distance of about 5 centimetres. The precise boundaries of the supraoccipital [soc.) are indistinct. In the middle line it, like the upper portion of the exoccipitals, is inclined forwards ; above it is hollowed out by a great median fossa, the floor of which is greatly roughened and is obscurely divided into halves by a slight median ridge. I'his fossa is one of the most characteristic ]ieculiarities of the skull of the later Elephants, but in Faheomasfotlon it is far more sharply defined, probably, ff)r the most ])art, on account of the smaller develo[)ment of the cellular tissue of the rest of the bone. 'I’he sides of the fossa an* formed by broadly rounded vertical ridges. The su])erior and su})ero-lateral ])ortions of the bone occupying the position of the lambdoidal crest are unfortunately broken away, but it can be seen that in conjunction with tlie neighhouring squamosals and parietals the body of the bone is excavated by a series of large cellular cavities, PAL^.OMASTODON. 133 resulting from the greoc., basioccipital ; fep., basisphenoid; eu., eustaebian opening ; exo., exoccipital ; f.l.m., foramen lacerum mc'dium ; fd-])-, foramen lacerum posted us ; /.o., foramen ovale ; p?., glenoid surface for mandible; i.c.c., foramen for internal common carotid ; i.n., internal nares ; ju., jugal ; m. 2, m. ‘A, second and third molars ; ])alatine ; p.p-f-i posterior palatine foramen ; ]xu’occi[)ital process ; , pterygoid ; post-tyitipanic ])rocess of squamosal ; st.rnf., stylo-mastoid foramen ; tympauo-byal ; ty., tympanic ; v., vomer, .j nat. size. eu I jell. hoc. ICC. form the floor of the inner end of the external auditory meatus. In front of this the bone is excavated by the deep fossa referred to above ; this seems to have opened into PAL^OMASTODON. 135 the skull and has in its posterior wall a foramen, the stylomastoid {st.mf.) ; in front of and internal to this foramen the tympano-hyal {tpJi.) seems to have been situated. Between this fossa and the basiocci[)ital the bone is perforated by a large foramen for the internal common carotid [i.c.c.). In front the bone is produced forwards and inwards into a sharp-pointed process lying along the basisphenoid and having on its inner side the opening of the eustachian canal {eii.). The anterior end of this process is continuous with the ridge formed by the posterior end of the pterygoid. The antero- external face forms the hinder border of the foramen lacerum medium and unites with the alisphenoid. The parietals {pa.) are unfortunately incomplete posteriorly, where, however, they must have united with the supraoccipital above and with* the squamosal below: they helped to form the thick lambdoidal ridge, in which, as above described, large air-sinuses communicating with the exterior by means of several foramina {for.) were developed. The parietals are only slightly convex from above downwards and incline towards one another at an angle of about 77°, meeting in a strong sagittal crest (s.c.), of which there is no trace in the modern Elephants. This peculiarity emphasises the primitive character of this skull compared with that of Elephas, in which the temporal fossae are separated by a broad expanse of skull-roof, flat or slightly convex, but with no trace of sagittal crest : the difference being in the main due to the fact that the development of the spongy diploe, carried to such an enormous extent in Elephas, is here only beginning and does not yet extend much beyond the occipital region. About opposite the anterior angle of the squamosal the sagittal crest divides into the supratemporal ridges, which diverge and no doubt terminated on tbe post- orbital processes, but unfortunately the whole of the upper part of the skull from about 7 centimetres in front of the origin of the supratemporal ridges is broken away in the specimen here described, and in the young example from which the account of the front of the skull is taken these ridges are scarcely at all developed. Anteriorly the parietals unite with the frontals, but in the present specimen only the lower portion of the suture can be observed ; from this it appears that the frontals meet the squamosals, so that the parietals are excluded from contact with the alisphenoid. T\\e frontals, nasals, premaxillm are wanting in the specimen upon which this description is based and will be described below from another example. The alisphenoid (text-fig. 49, als.) may be described as a triradiate bone. Its posterior portion forms the anterior boundary of the foramen lacerum medium, on either side of which it unites with the tympanic; externally it joins the squamosal, the suture with which runs just internal to the inner edge of the glenoid surface. This posterior portion is perforated by the large foramen ovale {f.o.) and further forwards by the posterior opening . of the alisphenoid canal {al.c.). The upper limb of the bone unites posteriorly with the squamosal, and for a short distance above with the frontals. Its anterior border, together with that of the lower limb, forms the prominent crest-like TP:RTrARY VERTERRATA OF TJIE FAY CM. 1 ;5G outer wall of tlie deep groove, at the bottom of which the foramen lacervm antervus { f.l.a.), i\\o foramen rotnndum, and the o])tic foramen open. This groove is continued downwards and forwards almost to the angle of the pterygoids and upwards on the frontals, ])robably terminating, as in Elejdias, at the postorbital process; in the recent form the u])per limb of the alisphenoid is relatively small, while the ventral or pterygoid wing is greatly expanded, owing to the great size of the molar sockets, which it, together with the pterygoid with which it is fused, embraces. In Palceomastodon the pterygoid wing of the alis])henoid is a comparatively narrow tongue of bone closely applied to and, in the adult, fused with the outer face of the pterygoid, and perhaps to a small extent in front with the palatine (PI. XII. fig. I, al.). The upper end of this portion of the alisphenoid is perforated by the alisphenoid canal [al.c.], the posterior opening of which, as already described, lies a little below and in front of i\\e foramen ovale ; while the anterior opening is at the bottom of the deep groove above referred to, and beneath the foramen lacerum anterius, with which probal)ly the foramen rotnndum also opened. The boundaries between the alisphenoid and orhitosplmioid cannot be determined. The optic foramen, which no doubt perforated the orbito- sphenoid as usual, lies at the bottom of the groove some distance above and in front of the foramen lacerum anterius, and a shallow groove marking the course of the optic nerve runs forwards from it to the orbit. The lower limit of the orbitosphenoid is obscure, but it appears to have united with the upper edge of the orbital plate of the ])alatine and perhaps also with the maxilla. The exact form of the [pt.) is difficult to make out. As usual it forms the posterior part of the lateral wall of the mesopterygoid fossa, embracing the basisphenoid above and dying away as a ridge which is continuous posteriorly with the anterior end of the tympanic ; its outer face is for the most part concealed by the adherent pterygoid plate of the alisphenoid, but on the inner side the sutnre with the palatine can be seen to run upwards and backwards from the posterior angle of the vertical palatine plates to the basisphenoid. The posterior vertical portion of the palatine {pi.) forming the side of the meso- pterygoid fossa is considerably thickened; posteriorly it joins the })terygoid in the manner already described, above it meets the vomer which extends back considerably behind the level of the hard palate, and together the two bones conceal the anterior part of the basisphenoid and the rest of the anterior part of the basis cranii. In front the bone becomes still more thickened, so that where its horizontal plate meets its fellow of the opposite side they together form not only a strong backwardly-directed process, but also a large paired downwardly-projecting tuberosity, and from this the line of union of the bones is continued forwards as a strong enstiform ridge which extends tliroughout their whole length and on to the maxilla in front. The anterior end of the })alatine plates is about opposite the hinder lobe of the second molar. The suture with the maxillae is transverse in front, then it runs backwards and outwards, being PAT;/E()MASTODON. 137 interrupted opposite the front lobe of the last molars by a pair of elongated apertures, the posterior palatine foramina {p-p-f-)- The upper edge of the palatine seems to extend up into the side of the skull above the maxilla, where it joins the lower edge of the orbitosphenoid. 'I'he vomer (text-fig. 49, v.), as already remarked, extends backwards considerably behind the level of the posterior border of the hard palate and forms a long V-shaped crest along the roof of the nasal canal. In this specimen the upper portion of the maxilla (mx.) is broken away in front, so that its relations in that direction cannot be determined. The alveolar region is very long and almost straight, there being only a very slight outward convexity ; it bears six cheek-teeth (three premolars and three molars). The base of the zygomatic process is long and nearly parallel with the alv^eolar border, from which it is separated by an interval of about 3 cm. : the anterior end is about opposite the front of m. 3. The upper surface is concave and forms the lower border and floor of the orbit. Anteriorly it is perforated by the antorbital foramen, which, judging from the young skull described below, had two openings on the face — a lower larger one preserved in the present specimen, and a smaller upper one here broken away. The much smaller size of the antorbital foramen in Palceomastodon compared with that seen in Elephas, is no doubt due to the fact that in the older form the proboscis was still comparatively small. Behind the orbit there is a small upwardly directed process of the zygoma, marking the anterior limit of the jugal, which sends forwards a long process overlapping the maxilla and helping to bound the orbit. The form of the suture between the jugal (jit.) and the maxilla {mx.) will be best understood by examination of the figure (PI. XII. fig. I). The palatine plates of the maxilla are rather narrow and together form a palate which is gently arched from side to side ; posteriorly they are separated by the palatines as above described. Behind the last molar the bone is greatly thickened by sinuses, so that, although the dentition is still of a perfectly normal type, the increase in the size of the hinder part of the maxilla, which is carried to such an enormous extent in the later forms, in which the teeth are greatly enlarged, has already begun to manifest itself. Superiorly the bone appears to unite with the orbitosphenoid in a straight suture running forwards and downwards. The anterior portion of the orbital region is wanting. The maxilla, as might be expected from the character of the dentition, differs widely from that seen in the Elephants. The chief differences are : (1) the much greater relative length of the bone ; (2) its smaller depth consequent upon the brachyodont character of the teeth. These features are especially noticeable posteriorly, where, except for the development of the sinuses in the bone behind m. 3, there is no trace of the enormous increase in size in all dimensions, but especially in depth, which has taken place in Elephas in consequence of the immeirse size of the posterior molars and their mode of J38 TEliTJARY YERTEBRATA OF THE FAYtiM. succession. The difFereiices between the palatines and pterygoids in the earlier and later ty])es are of course dependent on the same causes. d’he anterior portion of the skull, particularly the upper portion, is completely wanting in the large specimen on which the above description is for the most part founded ; but another specimen (PI. XIII.) supplies the necessary information concerning this region. It is the anterior ])ortion of a skull of a very young individual in which the milk-teeth are still in use ; it includes the whole of the frontals as far back as considerably behind the postorbital processes, the nasals, ])rcmaxillaries, lachrymals, and most of the maxillae, including the zygomatic process, also the palate as far back as the level of the middle of the zygoma. There are two teeth in situ on one side and three on the other ; they are probably mm. 2, 3, 4, and will be described below. The crushed base of one of the milk- tusks is ]n-eserved in the socket. As will be shown below, this specimen in the shortening of the nasals and the shifting backwards of the narial opening supplies a beautiful illustration of the approximation towards the later Proboscidean type found in this genus. In the relations of the bones to one another it precisely resembles The right frontal {fr.) is mostly broken away, but the left is better preserved, and although its actual junction with the parietal cannot be observed, nevertheless little can be wanting from its hinder border. Together the upper part of the combined frontals in the interorbital and part of the postorbital regions forms the gently convex skull-roof. In this young specimen scarcely any trace of the supra- temporal ridges (the divided sagittal crest) can be seen, but it is evident that they ran on to the postorbital processes. External to these ridges in the postorbital region the frontals run down into the temporal fossm, and are strongly convex from above downwards. The postorbital processes are blunt prominences, from each of which a ridge runs downwards and backwards, separating the orbit from the temporal fossa. Ventrally this ridge must have been continuous with that formed by the free edge of the alispheuoid described above. In front of the postorbital processes the frontals form a well-defined upper rim to the orbit, and anteriorly they unite in suture with the maxilhu, lachrymals, prcmaxilhe, and nasals, their general relationships to the neighbouring bones being exactly as in Elephas. The lachrymal {lac.) is a small bone wedged between the frontal and maxilla, and grooved below by the upper surface of the antorbital canal. It is ])erforated by a large foramen which lies within the border of the orbit ; above the foramen and on the rim of the orbit there is a small but prominent tubercle. The nasals [na.) are short bones which already approximate very nearly in form to those of Elephas. Together they ])roject in a blunt point over the nasal aperture. Eostc'riorly they are together roughly semicircular in outline and mute for the greater part of their width with the frontals, but externally to these with the premaxilla'. PAL^OMASTODON. 139 The '^remaxillm [pmx.) send up a long tongue of bone along the sides of the nasal opening, thus completely shutting out the rnaxillm from any share in its border. Anteriorly they are proloufied forwards, forming a projecting snout, on cither side of which are the alveoli of the large incisor tusks, which must have projected forwards and somewhat downwards. Here the only trace of teeth is a portion of the crushed base of one of the tusks (i.), probably of the milk-series ; this tooth seems to have been enamel-clad on the outer side only. On the palate the premaxillae seem to have appeared to a very small extent only, but the precise division between them and the maxillae cannot be made out. The upper surface of the conjoined bones is slightly concave from side to side, the first indication of the form so characteristic of the later Proboscidea. Posteriorly their median suture opens for a short distance in a sort of cleft ("? for the mesethmoid cartilage), on either side of which they are perforated by a small foramen. The floor of the nasal cavity is much more in the same straight line with the upper surface of the anterior part of the premaxilloe than in Ulephas, and the premaxillary portion of the snout, as a whole, is relatively much longer and narrower. The nasal opening (nar.), looked at from the front, is quadrate in outline ; its upper posterior angle lies considerably in front of the orbit and only a little behind the level of the facial opening of the antorbital foramen. In Elephas, on the other hand, the great difference is that the nasal opening is largely behind the anterior border of the orbit, and the whole facial region is much shortened up. The maxiUce [mx.) are not completely preserved posteriorly. In front the facial portion extends up the side of the face to the level of the top of the nasal opening, and helps to form the anterior border of the orbit. The base of the zygomatic process is perforated by a large antorbital canal, which opens on the face by two foramina (a.o.f.) — the upper small, the lower much larger. The process itself is stout ; it forms the lower border of the orbit, but posteriorly the postorbital process is actually formed by the anterior end of the overlapping jugal (ju.) above described. The palate is fairly broad and is slightly arched ; it narrows in front, where the maxillae seem to run forwards beneath the premaxillae as in other Proboscideans. A restoration of the whole skull founded upon the two specimens above described is given in text-fig. 48 (p. 131). Upper Dentition (PI. XII. figs. 1, 1a; PI. XIV. fig. 2). — In the upper jaw there are seven teeth on each side : viz., an incisor {i. 2), three premolars, and three molars. The first molar is always much smaller than the others. The incisor is a large, laterally compressed, downwardly directed tusk, sometimes with a slight spiral twist; the anterior edge is rounded, the posterior sharper. There is a broad band of enamel on the outer face. One nearly complete specimen measures 25‘3 cm. long in a straight line. Behind the tusk there is a diastema of at least 9-10 cm. T 2 140 TERTIARY VEHTERHATA OF THE FAYCxAI. 'I’he aiitcvior ))rem(0ar {pm. 2) is a simple, blunt, somewhat laterally compressed cone, of which tlie anterior slope is much shorter than the posterior. This latter is worn into a broad flat surface looking slightly inwards. There are no accessory cusps, but the cingulum is fairly well developed, especially on the inner side, where it is often somewliat crenulated or divided into small separate prominences. The next tooth {pm. d) consists of a larger outer and a somewhat smaller inner cusp arranged transversely. There is a small ])03tero-interiial cusp, lying behind and closely connected with the inner main cusp : this posterior cusp may sometimes be nearly absent. The cingulum is well developed, especially on the anterior and posterior faces of the tooth, where it forms small projections. The last premolar [pm. 4) is a bilophodont tooth, each crest consisting of a pair of cusps — the outer higher and more com])ressed, the inner more rounded and coming into wear first. The inner cusps in this ]iremolar already show a tendency towards a V -shape, the point of the V being turned inwards ; this form is the consequence of the presence of obscure and imperfectly separated tubercles on the antero- and postero-external sides of the inner tubercles. The anterior accessory tubercle of the front V and the posterior accessory tubercle of the posterior V become fused with the cingulum of the anterior and posterior ends of the tooth respectively. The other accessory tubercles form a bridge across the main transverse valley. The cingulum is well developed on the ends and outer side of the tooth, where it is strongly crenulated. The molars m. 1 and m. 2 are trilophodont, each ridge being composed of a pair of cusps similar to those described as occurring in 4, the chief difference being that in m. 1 and m. 2 the posterior accessory tubercle of the last inner cusp is larger and, by its union with the posterior border of the tooth, forms the first trace of a fourth transverse ridge. The cingulum is well developed, particularly on the inner side of m. 2. The last molar may be said to consist of two transverse crests and a talon. The anterior accessory tubercles of the inner cusps are especially well developed. The talon consists of three tubercles, of which the innermost is much the largest, and the outer two are sometimes imperfectly divided. The crenulated cingulum is well developed, particularly on the anterior and inner faces. The above account of the upper teeth applies to specimens referred provisionally to P. headnelU, but which may probably belong to F. wintoni : this applies to both the skull figured on PI. XII. and to the upper teeth figured on PI. XIV. fig. 2. The species being founded mainly on the form of the mandible and of the last lower molar, ic will not be possible, in most cases, to determine the skulls and upper teeth with certainty till specimens have been found associated with the mandibles. Upper Milk-dentition (PI. XIII.). — The u])per milk-teeth are preserved in the specimen upon which the account of the front of the skull is founded. In this, in addition to remnants of the base of the milk-incisor, there are on the left side three PALiEOJVIASTODON. 141 otlier teetli (PL XIII. fig. 1 b), which arc regarded as being mm. 2, 3, 4, while on the right only the two anterior ones are ])reserved. j\Im. 2 consists of a large main cus]), laterally comy)ressed and having a small accessory ensp on its ])osterior edge. The cingnlnra is well developed on the front of the tooth, where it forms a small cusp ; it is also present on the inner side, and forms the edge of the ])rominent postero-internal angle of the tooth. Mm. 3 is a somewhat elongated tooth, wider behind than in front. Its anterior angle is formed by a cusp of the cingulum. The rest of the tooth is bilophodont, each transverse ridge consisting of a pointed outer cusp (scarcely at all worn in the present specimen) and a rounded lower inner cusp (here much worn). There seems also to have been a posterior cusp forming a sort of small talon and becoming continuous in wear with the postero-internal main cusp. The cingulum is present on the front of the tooth, at the inner end of the transverse valley, and on the outer side of the posterior half of the tooth. Mm. 4 is trilophodont : the anterior ridge is composed of an outer sharper cusp and a blunter inner one ; the other ridges are similar, except that the outer cusp is somewhat compressed from before backwards. The anterior angle of the tooth is formed by a projection of the cingulum, which also appears at the inner ends of the transverse valleys and on the hinder end and the posterior half of the outer side. Mandible (PI. XIV. fig. 3 ; text-figs. 48, 53, 54). — The mandible is very long and must have projected a considerable distance in advance of the skull. The symphysis (PI. XIV. fig. 3, sym.) is greatly elongated and somewhat decurved : its upper surface forms a spout-like groove bordered by the sharp edentulous alveolar border ; the groove is deepest in the middle, but with the rest of the symphysis widens out tovvards the sockets of the incisors, the upper faces of which continue the spout-like surface forwards. Ventrally the symphysis is deeply channelled in the middle line between the alveoli of the incisors. Immediately beneath the third premolar (the first here present), which is situated at a varying distance behind the posterior end of the symphysis in the different species, the horizontal ramus deepens considerably ; it is flat on the inner face and strongly convex from above downwards externally. The ascending ramus arises from the outer face of the jaw, its anterior border being opposite the anterior lobe of the last molar. This anterior border slopes slightly backwards and terminates above in a very small backwardly curved coronoid process (text-figs. 53, 54, cor.). Behind this the upper border of the ascending ramus is gently concave as far as the con- dyle [cond.), which is rather higher than the coronoid process and is slightly convex from side to side and very strongly so from before backwards. From it a broad rounded thickening runs down to the posterior end of the alveolar border, and this ridge is most strongly marked on the inner face, where immediately beneath it, and midway between the end of the molar series and the hinder border of the jaw, there is the very 112 TERTIARY VERTEBRATA OF THE FAYtM. large round opening of the dental canal. Beneath this ridge the angular region is thin, concave on the inner face, and convex externally ; the angle itself is broadly rounded. On tlie outer face of the jaw, a little below and in front of the condyle, there is a ])roniinent rounded surface for the attachment of a powerful muscle. The ascending ramns, as a whole, is slightly inclined backwards. Lower Dentition (PI. XIV. figs. 1, 3, PI. XV. fig. 1 ; text-figs. 50, 53, 54). — The lower incisors (PI. XIV. fig. 3) are straight procumbent teeth, probably representing 2 of the full series. Ventrally they are convex from side to side, dorsally concave ; the outer and inner borders are nearly straight and parallel in the unworn portion. The anterior end is worn above, so as to produce a chisel-shaped surface convex in outline ; the enamel covering the ventral face is comparatively thick, while on the dorsal face it is very thin and in some cases perhaps wanting. The outer edge of the tooth is comparatively thin, the inner much thicker. The two teeth are in close contact in the middle line and their concave upper surfaces together form a forward continuation of the spout-like symphysis. The ventral face is usually marked by a series of broad shallow longitudinal grooves. Only two premolars (text-figs. 53, 54) are present in the lower jaw. Of these 3 is a comparatively small laterally compressed tooth consisting of a large pointed main cusp, which in some cases gives some indication of comprising two united elements : behind this there is a small obscure cusp and on the anterior and posterior ends of the tooth the cingulum forms slight projections. In the type specimen of P. headnelli this tooth is missing. Pni. 4 is much more complex, being a bilophodont tooth, each crest consisting of a pair of subequal cusps. There is also a small but distinct intermediate cirsp lying between and uniting the inner ends of the two outer main cusps. On the middle of the anterior end of the tooth is a closely adpressed cusp belonging to the cingulum, and towards tlie outer side of the posterior end a similar but much smaller element. The peculiarities of these premolars and their differences from the corresponding teeth of Moeritlterium seem to be the consequence of two distinct influences — one the tendency to the reduction and loss of the anterior members of the series, the other the tendency to the increasing complication of the posterior ones. The consequence of these influences is that^u?i. 2 has disappeared altogether, 3 is reduced in relative size and sinq)ler than tlie corresponding tooth in Mceritherium, while pm. 4 is hilophodont and much more molariform than in the earlier genus. The molars (PI. XV. tig. 1 ; text-figs. 50, 53, 54) are all trilophodont, differing only in the several species in the degree to which the main cusps liccome subdivided and in the complication of the talon of m. 3. The anterior molar is much smaller than those behind. The following description refers especially to the type species, P. headnelii., the differences in the other species being noted below. The molars are trilophodont, each crest consisting of a pair of tubercles, of which PALJilOMASTODON, 143 the outer one is the more rounded and always much more worn than the inner, which is higher and somewhat compressed from before backwards. The outer cusps, particularly the anterior ones, often give a roughly V-shaped surface in wear, the point of the V being turned outwards: this results from the presence of small and slightly developed accessory tubercles connected with the inner side of the main outer cusps. In the case of the anterior cusp the front accessory tubercle is fused with the cingulum, while the posterior one partly fills the valley between the first and second ridges. In the last molar the posterior accessory tubercle of the last outer main cusp is larger and is connected with the cingulum, forming a small and slightly developed talon. In some other species this is much larger, and the Text-fig. 50. A. C. m.5. The second and third lower molars of : A, Palceomastodon beadnelli (left side) ; B, P. ^vintoni (left side) ; C, P. parvus (right side) ; D, P. minor (right side). All | nat. size. accessory tubercles are better developed. The cingulum is only slightly developed : in some cases it forms small blunt tubercles opposite the inner ends of the transverse valleys (see PI. XV. fig. I, m. 2). Vertebral Column. — The vertebral column in the present genus is not well known, because the absence of specimens occurring definitely associated with portions of the skull and mandible, together with the intermingling of vertebrse of other Ungulates of similar size, makes it almost impossible to determine isolated vertebrae. In the case, however, of highly characteristic vertebrae like the atlas and axis, some degree of certainty may be attained. These two vertebrae are here described from specimens 144 TERTIAliT VERTEBRATA OF THE FAYtjM. found in the immediate neighbourliood of the type mandible of P. headnelli, and from their size probably referable to that species. Other specimens differing only in their smaller dimensions will he found mentioned in the Catalogue, where they are referred provisionally to other species. 'fhe ailas of P. headnelli (PI. XV. fig. 3) is of very large size, equalling the same \ ertebra in a small Indian Elephant. The condylar cups (cond.) for the occipital condyles are deep ; they are wide dorsally, hut narrow considerably towards their lower end. The articular surface for the skull is rather wider and lower than in Mastodon or Elephas, in which the long axis of the condylar cups is nearly vertical. The arch forms a low nearly straight bar, which bears on its dorsal surface a median transverse ridge {n.sp.) separating an anterior rugose surface for the attachment of muscles from a nearly smooth posterior one. Anteriorly the base of the arch is perforated by a foramen for the transmission of the first spinal nerve. In Elephas and Mastodon the arch is more elevated and shorter from side to side. The ventral bar is likewise longer and straighter than in those genera, though some species of Mastodon (e. g., M. americanus) approach the present form in this respect. The notch for the odontoid process (o^k) is broader and shallower than \\\ Mastodon., Elephas primi genius, and P. maximus, in which it is comparatively narrow and deep ; E. africanus resembles Ealceomastodon most nearly in this respect. The distinct separation of the odontoid notch from the neural canal distinguishes the atlas in this genus from that of Arsinoitheriimi. The posterior surface for union with the axis differs widely from the form seen in the atlas of other Proboscidea. In these the lateral surfaces for articulation with the centrum of the axis are continuous both with that for the lower surface of the short blunt odontoid process and with one another beneath it. In PaUeoinustodon, on the other hand, the two lateral surfaces, which make only a small angle with the transverse plane, are distinct from one another and are not continuous with the odontoid facet, which is a cylindrical surface on the upper face of the ventral bar ; this latter bears on its postero-ventral border a blunt hypaj)opbysial process. The transverse processes {tp.) are about the same size as in the Indian Elephant ; they are ])erforated at their base by a foramen (t’.c.) which is much smaller than that found in the atlas of Mastodon and Elephas. The upper pedicle of the transverse process is much wider than the ventral one ; the anterior face of the transverse ])rocess looks downwards and forwards. On the whole, this vertebra approaches very nearly to the atlas of the Elephant, differing from it mainly in (I) the form and relations of the surfaces for articulation with the axis ; (2) the smaller size of the vertebrarterial canal ; (3) the more oval oiitline of the surface for articulation with the skull. The axis (PI. XVI. figs. I, I a) differs much more widely from the modern Pro- l)Oscidean type than does the atlas, and at the same time ap]U’oximates more nearly to the form seen in some Ungulates (e. g., Jlippopotanins) with necks of moderate length. The odontoid process (od.) is large and somewhat comj)ressed laterally ; its ventral PAL.EOMASTODON. 145 border is in the same line witli the hypapophysial ridge on the centrum : on its lower surface it bears an oval facet for articulation with the ventral bar of the atlas, this facet being sharply defined and separated from the lateral articular surfaces, which arc oval in outline and make an angle of aboiit 115° witli the long axis of the odontoid process. The centrum is very long compared with that of the later Proboscidean axis ; it bears a median hypa])ophysial ridge, which deepens posteriorly in such a way that the posterior articular surface is greatly deepened ventrally. There are small transverse processes [t.]).) perforated at their base by a large vertebrarterial foramen. The neural arch is very high, but the precise outline of the spine [n.sp.) cannot be determined, owing to the imperfection of the specimens ; it can be seen, however, that it was high and broad, and overhung the arch both before and behind. A smaller axis vertebra, in which the neural spine is nearly complete, shows that it consisted of two plates meeting- in front at an acute angle and enclosing posteriorly a deep fossa for the insertion of muscles or ligaments. This axis differs from the ordinary Proboscidean type in the following points: — (1) the large size of the odontoid process, which in the later forms is reduced to a mere knob with its articular surface continuous with that of the centrum which extends beneath it ; (2) the much greater length of the centrum ; (3) the less massive, but much higher, neural spine. On the other hand, it is very similar to that of Mceritherium. The neck in Palceomastodon was probably considerably longer and more mobile than in the later Proboscidea. Fore Lwih. — An incomplete left scapula collected in the same locality as the type mandible is the only evidence of that bone yet discovered. It is very closely similar to the scapula of Elephas, differing only in the rather slighter prominence of the coracoid process and in Avidening out less rapidly posteriorly above the glenoid cavity, the whole blade being probably rather less expanded above than in Eleplms. The glenoid cavity is an elongated oval, the prescapular fossa is extremely narroAv, and the process projecting backwards from the middle of the spine in Elephas here seems to be situated a little nearer the glenoid end. In the case of the humerus (PI. XVI. figs. 2, 2 a) also the only specimen that can be definitely determined as belonging to Palceomastodon beadnelli, was collected near the type mandible. In its general character this bone is like that of the later Proboscideans, but is somewhat stouter and broader in proportion to its length, and approaches more nearly some specimens of the humerus of Mastodon Avith Avhich it has been compared. It is also very similar to the humerus figured by de Blainville (‘ Osteographie,’ Atlas, vol. v. pi. xiii., Elephas) as that of Tetrahelodon angustidens. The deltoid crest [d.) is greatly developed and strongly bent over to the outer side of the bone. The very prominent and Avell-marked supinator ridge {sp.r.) is shorter than in the Elephants, though still very large ; its flat outer surface is slightly inclined to the long axis of the shaft. The inner trochlea is much larger than the outer, and, in fact, seems to be larger proportionately than in the Elephants ; bnt in u IlG TERTIAIiY VEUTEBRATA OF THE FATCM. tliis respect also it ai)proxiitiates to a humerus of Mastodon with which it has been compared. The olecranon fossa (o./*.) is just as in Mephas, and the distal view of the lower end of tlie humerus is almost precisely like that of a humerus of Elephas meridionalis figured by Adams (‘ llritish Fossil Elejdiants,’ pi. xvi. fig. 3). Hind Limb. — Tn the same locality was found a portion of a right os innominatuni consisting of the acetabulum and the acetabular ends of the pelvic bones. This specimen differs in no important respect from the same region of the pelvis of the later Froboscidea, while, on the other hand, it is very unlike what is seen in the pelvis of ylrsinoitherium, the only other animal with which confusion would be likely. The very large acetabulum is perhaps a little more circular in outline than in Elephas, and at the same time the cotylar notch is wider and the pit for the ligamentinn teres is deeper. 'The ischium is much more flattened and thinner than in Elephas and its postero- su])erior border forms a prominent crest-like ridge. The pubis is like that of Elephas. The upper end of the obturator foramen is like that of the African Elephant and is not, as in the Indian Elephant and the Mammoth, marked off into a sort of notch by a projecting point of bone. This specimen differs from the pelvis of Arsinoitherium in the following points : — (1) the acetabulum is nearly circular in outline, in Arsinoitherium it is oval ; (2) the cotylar notcli is much broader and the pit for the ligament larger and deeper; (3) the obturator foramen seems to have been relatively much larger; (4) the ischium is broader, thinner, and flatter. In short, it may be said that this specimen differs from the pelvis of Arsinoitherium in almost exactly the same respects as docs the pelvis of Elephas. A femur (El. XVI. figs. 3, 3 a) from the same locality is the only specimen of that bone in the collections of Cairo and London that is definitely Proboscidean in character and can be referred to Palceomastodon — a circumstance which still further emphasises the extraordinary rarity of bones of the skeleton of that animal. The head is nearly hemispherical ; it rises considerably above the great trochanter and bears a deep pit for the ligament um teres (not shown in figure) in the middle of its jmsterior half. The neck, which is directed obliquely upwards, is greatly compressed from before backwards. The head (Ji.) rises less above tlie great trochanter than in E. africanus, but more than in E. maximus. The great trochanter {g.t.) is developed to about the same extent as in the femur of Mastodon ; the smaller is represented by a slight ridge. The digital fossa is merely a shallow concavity, dying away distally on the flat posterior surface of the u])])er half of the shaft. In its middle portion the hinder face of the shaft is convex and is ])roduccd outwards into a prominent ridge {t.t.), which seems to represent the third trochanter ; this is also developed to some extent in the Mammoth femur, but scarcely at all in the recent Elephants. In a femur of Tetrabelodon angustidens figured by de Plainville (‘ Osteographie,’ Atlas, vol. v. pi. xiii., Elephas) this ridge is well developed, but is rather lower down the shaft than in Ealwomastodon. At the distal end of the bone I’ALiI':OMASTO])ON. 147 the condyles o.c.) are siibcqnal, as in E. maximuH •, they are separated by a deej) intercondylar fossa, which extends into the inner face of the condyles and is crossed obliquely by a ridge running down from the upper inner end of the outer condyle, 'file trochlear surface is too much broken in this specimen for description. A left tibia (PI. XVI. figs. 4, 4 a) from the same locality is, on the whole, like that of the Elephant. It is, however, rather more slender in the shaft, and the distal articulation differs in several important points. At the proximal end the articular surfaces are somewhat more obliquely placed than in Elephas, the inner facet (7.) being somewhat more elevated with regard to the outer (o.) ; the two facets are of nearly equal size. The upper end of the cnemial crest (cn.) is slightly more prominent in proportion to the thickness of the shaft than in the Elephant, and both in this and in the other points mentioned there seems to be a greater likeness to the tibia of Tetrabelodon. On the middle of the front of the shaft there is a vertical groove-like depression for the insertion of a muscle. The distal end differs from that of the tibia of Elephas in the following points: — (1) the internal malleolus {i.m.) is much more prominent and is sharply bounded on its astragalar side by a well-defined groove ; (2) the astragalar surface is more strongly concave from before backwards and posteriorly is produced downwards into a prominent point near its inner side ; (3) the surface for the fibula is smaller and situated further back. The whole surface indicates that the tibial face of the astragalus was narrower and more convex from before backwards and interlocked much more closely with the tibia than in Elephas ; the broad, gently convex, tibial surface of the astragalus in the later Proboscidea not being a primitive character of the group. Immediately above the internal malleolus there is on the postero-internal face of the shaft a short deep groove, bounded internally by a strong ridge : this is wanting in the tibia of Elephas. No bones of the foot were found with the limb-bones just described, but a single calcaneum (text-fig. 51), from some distance off, so nearly resembles in essential characters the calcaneum of the later Proboscideans, more particularly of the Lower Miocene Tetrabelodon angustidens, that it may be safely referred to Paleeomastodon.., and from its large size probably belongs to P. headnelli. As might be expected in an animal considerably more lightly built than Elephas, the calcaneum is more elongated, the tuber calcis {t.c.) especially being less short and stout. In its general proportions this calcaneum more nearly resembles that of Tetrabelodon angustidens-, but even in this Lower Miocene form the bone is already considerably shorter and stouter. There is a large fibular facet much like that seen in the calcaneum of Elephas, except that, instead of narrowing gradually from before backwards, it terminates posteriorly abruptly in a nearly vertical border ; it is convex from before backwards and looks upwards and outwards. Of the two surfaces for the astragalus the ectal {ec.) is the larger; it is nearly flat, only rising a little towards the anterior part of its outer border, where it meets the upper edge of the fibular surface. u2 148 TERTfAliY YERTEBRATA OF THE FAYlJM. 'I'lio sustoiitaciilar facet (sxs.) is separated from the ectal posteriorly by a deep groove which enlarges anteriorly into a deep fossa ; this surface is convex from before back- wards and anteriorly it is continued forwards and outwards as a narrow strip along the to]) of the anterior edge of the above-mentioned fossa, and in front of this it is continuous with the small surface for the navicular which meets it at about a rio-ht amrle. The sustentaculum, as a whole, is prominent and sharply defined. The cuboid surface (cub.) Text-fig. 51. Left calcaneum of Palceomastodon heachielli : A, from above ; B, distal end. cub., facet for cuboid ; ec., ectal facet ; sms., susteutacular facet ; t.c., tuber calcis. The libular facet lies immediately outside the ectal facet. | uat. size. is much like that seen in Elcjjhas, but is narrower and does not extend so far towards the inner side of the bone ; it is gently concave. Jleneath and to the inner side of it there is a roughened surface which ventrally passes into a prominent tuberosity. The outer face of the calcaneum is concave from above downwards, while the inner side of the t/fber calcis is slightly convex, the whole tuber being much more compressed laterally than in Elephas, though perhaps not more so than in Tetrabelodon amjustidois. }so astra(jalas largo enough to have belonged to P. beadnelli has been found; but a PAL^OMASTODON. 149 number of smaller ones, which appear to have belonged to Proboscideans, occur in the collections. The largest of these is shown in text-figure 52, and may be referred pro- visionally to P. imntoni. The tibial surface {tih.) is comparatively narrow from before backwards and is strongly and evenly convex in the same direction ; at its outer edge it is continuous with the nearly vertical surface for the fibula {,fih.), and on its inner side it is cut into by a deep rounded concavity [i.m.) looking upwards and inwards, evidently for the reception of a large internal malleolus such as has been described as occurring in the tibia of Palwomastodon (see above, p. 147). Behind this the postero-internal angle of the bone is produced into a strong tuberosity which in some of the smaller specimens forms a pedunculate knob. In front of the tibial surface the anterior face of the bone is concave and forms a short neck for the prominent rounded Text-fig. 52. 2. 5. Eight astragalus of Palaomastodon : A, from above ; B, from below. eet., ectal facet ; Jib., flbular facet ; i.m., surface for internal malleolus of tibia ; nav., navicular facet ; sus., sustentacular facet ; tib., tibial facet. | nat. size. navicular facet {nav.), which is almost precisely as in the astragalus of Tetrahelodon angustidens. There are two calcaneal surfaces : of these the ectal {ect.) is flat and nearly triangular in outline, the apex being anterior, while the sustentacular (sms.) is an elongated oval facet with the long axis antero-posterior, in which direction it is deeply concave. The anterior edge of the sustentacular joins the lower edge of the navicular facet. The two surfaces are separated posteriorly by a deep groove, wdiich widens out in front into a broad fossa, the anterior border of which is formed by the lower edge of the navicular surface. The chief differences between this astragalus and those of the later Proboscidea are: (1) the tibial surface is narrower and at the same time more strongly convex ; (2) there is a large internal malleolus in the tibia involving the presence of a deep concavity in the astragalus for its reception; (3) the neck is somewhat better developed, at least in the smaller species ; (4) the postero- internal angle of the bone is very prominent. 150 TERTIAEY VEETEBRATA OF THE FAYOM. PalsBomastodon beadnelli, Andrews. [Plates XII.-XVI. ; text-ligs. 50 A, 61.] 1901. Paloiomastodon headnelli, 0. W. Andrews, Tagehlatt des V. Internationalen Zoologen-Con- gresses Berlin, No. G, p. 4 (Verhandlungen, p. 528, 1902) ; Zoologist, [4] vol. V. p. .319; Geol. Mag. [4] vol. viii. pp. 401-403, fig. 1 (mandible). 1903. „ „ C. AY. Andrews, Phil. Trans, vol. 19G B, pp. 110-113, figs. 10-13 (skull and mandible). 1904. ,, „ C. W. Andrews, Geol. Mag. [5] vol. i. pp. 112-115, fig. 2 (skull). Type Specimen. — Left ramus of mandible with pn. 4 (broken) and m. 1-3 (PI. XV. figs. 1, 1 a); Geological Museum, Cairo. The type species and the largest yet known. The length of the molar and premolar series in the lower jaw is 28 cm. The molars are distinguished by the comparatively small development of the accessory and intermediate cusps and the antero-posterior com- pression of the main cusps, the consequence of these peculiarities being that the teeth are more distinctly lophodont than in the other species, with the exception of the small P. minor. The last lower molar has no talon beyond a slight ridge of the cingulum, which is almost as strongly developed in ni. 2. The molars also differ from those of P. vointoni and P. minor in being wider in proportion to their length ; in this respect they resemble the molars of P. parvus. The elongation of the mandibular ramus between the anterior end of the cheek-teeth and the symphysis also distinguishes P. beadnelli from P. wintoni and P. minor, in which the posterior end of the symphysis is very little in front of the anterior premolar [pm. 3) : in P. beadnelli the interval is about 12 cm. The degree to which the symphysis is prolonged in the present species is uncertain. The mental foramen opens almost immediately beneath the anterior end of pm. 3, and therefore some distance behind the symphysis. Form. & Log. — Fluvio-niarine beds (Upper Eocene) : north of llirket-el-Qurun. C. 10014. Imperfect left rumus of mandible with ptm. 4 and m. 1-3. The typo specimen noticed in ‘Tagehlatt des V. Internationalen Zoologen-Congresses,’ No. G, {>. 4 (Berlin, 1901) ; also described and figured in Geol. Mag. [4] vol. viii. (1901) p. 401 ; also IT. XV. figs. 1, 1a. The dimensions (in centimetres) of this specimen are : — Total length of specimen 61 Depth of ramus in middle of diastema 9*6 „ ,, immediately in front of i’> • • • - 10-5 „ „ ,, beneath pm. 4 12 PALiEOMASTODON BEADNELLI. 151 The dimensions (in centimetres) of the teeth arc : — Length. Width. prn. 3 (alveolus only) 4-1 jrm .4 4-8 3’3 app 4-8 3’7 app. 6-5 5-1 7-8 5-3 Approximate lengtli of molar and premolar series 28-5. M. 8059. Plaster cast of the above specimen. Made in the British Museum, llie following specimens were collected in the immediate neighbourhood of the type specimen ; from this circumstance, together with their large size, they may be referred to the present species with reasonable certainty : — C. 10014 a. Portion of left maxilla with greatly worn m. 2 and m. 3. This specimen is figured on PI. XV. fig. 2. The approximate dimensions (in centimetres) of the teeth are: — Length. Width. m.2 5'6 4'8 ' m. 3 6’5 5'2 M. 9234. C. 10060. M. 9120. C. 10061. M. 9121. C. 10016. M. 9235. C. 10013. M. 8060. C. 10062. Plaster cast of the above specimen. Made in the British Museum. Atlas vertebra from same locality. Figured (partly restored from another specimen) PI. XV. fig. 3. Width between outer edges of condylar cups 24’5 cm. ; total height 14'7 cm. Imperfect atlas vertebra from same locality. Presented hy the Egyptian Government^ 1904. Atlas vertebra from same locality. Figured on PI. XVI. figs. 1, 1 A. Total length from end of odontoid to postero-inferior point of centrum (approx.) 17 cm.; width of anterior end of centrum (approx.) 20 cm. ; height 20 + . Imperfect axis from same locality. Presented hy the Egyptian Government, 1904. Left scapula from same locality. Suprascapular and much of postscapular region broken away. Length of glenoid surface (approx.) 13 cm., width (appi’ox.) 8 cm. Plaster cast of the above specimen. Made in the British Muse^im. llight humerus, wanting the proximal portion, from the same locality. Figured on PI. XVI. figs. 2, 2 A. The dimensions (in centimetres) of this specimen are : — Length (so far as preserved) Gl Width of shaft at narrowest point 10 „ distal articular surface 19 ,, distal end at condyles 21 app. Length of supinator ridge 18‘5 app. Plaster cast of above specimen. Made in the British Museum. Portions of right os innominatum from same locality, including the acetabulum and the acetabular ends of the pelvic bones. Longest diameter of the acetabulum 13 cm. 152 TERTIARY VERTEBRATA OF THE EAYtM. C. 10017. Iliglit femur from same locality. Figured on PI. XVI. figs. 3, 3 a. The dimensions (in centiioetres) of this sj)ecimen are: — Length 87’o Longest diameter of head 12-3 Width of proximal end 28 „ middle of shaft above third trochanter 12 „ distal articulation 17’2 ,, distal end at widest point 19'7 M. 8061. Plaster cast of the above specimen. C. 10015. Left tibia from same locality. Figured centimetres) of this specimen are : — Length Width of proximal end .... „ distal end „ shaft at narrowest point ALade in the ]3ritish Alnseiim. on PI. XVI. figs. 4, 4 a. The dimensions (in 33-5 20 13-5 . . . 8 M. 9236. Plaster cast of above specimen. Made in the British Aluseum. M. 9231. Imperfect left tibia. Presented htj the Egyptian Government, 1904. M. 8484. Left calcaneum, probably of the present species. Text-fig. 51. The dimensions (in centimetres) are : — Extreme length 19 „ depth of anterior end 9‘8 AVidth of astragalar surface 9-5 ,, cuboid surface 6’3 Presented Inj TP. E. de Winton, Esq., 1903. The following specimens may be provisionally referred to F. headnelli, for, in the absence of associated series of bones, especially of upper and lower jaws, it is im])ossible in many cases to be certain of the specific determination. Since, however, many of these specimens have been found in the immediate neighbourhood of mandibles similar to that u])on which F. u-intoni has been founded (see below, p. 15G), and since that species appears to have been the commonest in the.se beds, some at least will no doubt eventually be referred to it. M. 8464. iSkull, wanting jmrt of the supraoccipital and most of the facial regions ; the cheek-teeth are preserved on the left side. Figured PI. XII. and text-Hg. 49 A. The description of the skull in this genus given above is founded so far as possible on this specimen. The dimensions (in centimetres) of this specimen are : — Greatest length (so far as preserved, see PI. XIL) .... 63-5 AVidth at zygomatic arch 42 „ external auditory opening 32'2 Height from junction of basioccipital and basispbeuoid to sagittal crest 22 Width of palate between in. 2 7 „ foramen magnum G’3 Height of foramen magnum 3'7 AVTdvh between outer angles of occipital condyles .... l(i'2 „ of glenoid surface 9-2 „ between inner ends of glenoid surfaces 14 H eight of opening of internal nares 5 o PA ASTO DON I5EA DNELLI. 153 'Pile (liniensions (in centiinef res) of (lie teeth are : — jnn. 3 pm. 4 1 m. 2 ?». 3 Length of molar series 15-5. Length. Width. 3 3 3 3-1 5*5 3-9 6-2 4-4 Length of preinolar series 10 (app.). Presented hy W. E. de Winton, Esq.., 1903. C. 8458. Base and palatal portion of skull. The left maxilla, part of right maxilla, and left zygomatic arch preserved. The figure of the skull given in Phil. Trans, vol. 19G u, 1903, p. 110, figs. 10, 11, was founded upon this skull. The dimensions (in centimetres) of this specimen are : — Width of skull at zygomatic processes 38 „ palate between m. 2 5'6 „ foramen magnum 7 Height of foramen magnum 4'5 app. Width between outer angles of occipital condyles .... 17 „ of glenoid surface 9-1 Length from ventral edge of foramen magnum to posterior border of hard palate 23' 1 'The dimensions (in centimetres) of the teeth are : — Length. Width. pm. 2 4 2-3 pm. 3 3'8 2-9 pm. 4 3-8 3-5 m.l 4 5 3-4 m.2 0-1 4-7 »i.3 G-1 5'1 Length of molar series 17. Length of molar and premolar series 28’4. C. 9225. Palatal portion of skull with pm. 3, 4 and m. 1-3 on left side : on right pm. 3 is wanting. Length of molar series 15‘7 cm. The last molar just come into wear. C. 9354. Lower portion of skull. The dimensions (in centimetres) of this specimen are : — Length from condyles to tip of snout 60 '5 „ ,, hinder border of palate 26 The lengths (in centimetres) of the teeth are : — pm. 3 pm. 4 m. 1 m.2 m.'d Length of molar series 15'6. 3 3- 1 4- 4 5- 4 6- 1 TEirriAKY YERTEBliATA OE THE EAYtM. 1 T) J M. 8383. ’alatal portion of skull with HI. 1—3, jnii. 3 , 4, and broken base ofpju. 2 on dinuMisions (in centimetix ‘s) of the teeth are : — Length. Width. )>iii. 2 (base only) . . 3-7 . . Jim. 3 CO Jim. 4 . . 3-4 3-2 m. 1 . . 4-5 3-4 m. 2 . . ()-3 4-3 m. 3 44 Length of molar series 15 5. Length of premolar series 10. Presented hy the EgyjMan Government, 1902. M. 8852. Palatal portion of skull with m. 1-3 and pm. 3-4 on left side, m. 2, 3 on right. Length of molar series 14'5 cm. Presented hy the Egyptian Government, 1904. C. 8111. Palatal region and basis of skull : the right zygomatic arch also ])resent. The form of the ])alate is well shown in this specimen ; it is slightly concave from side to side and is widest opposite m. 1, where its width is 7'5 cm. The maxillae diverge slightly from one another in the middle line and end in a point anteriorly : at the upper and outer side of this anterior region there is a deep concavity running forwards and downwards and marking the jiosition of the alveolus of the tusk, so that, as in Moeritlieriinn and Elephas, the maxilla seems to have extended forwards beneath the premaxilhe and helped to sui)]iort the tusks, and may even have formed part of the hinder border of their alveoli. Length from occipital condyle to ends of maxillte 66 cm. The dimensions (in centimetres) of the teeth are : — Length. Width. p;?!. 2 3'S 2T pm. 3 3-1 2-5 jmi. 4 3'2 3T m. 1 4-2 2-9 m. 2 5’0 4 m. 3 7 4-7 Ijengtli of molar series 17. Length of premolar series 10-2. C. 9398. Palatal portion of skull of a young individual in which m. 3 is not yet cut and pin. 4 has just appeared. The ])osterior end of m. 2 is op[)osite the hinder border of the ])alate. This specimen also shows the orbit, portions of the ])rema.xill:fi, and the nasal opening. The lengths of the t(mth (in centimetres) are : — m. 2, 5'9 ; in. 1, 4‘5 ; pmi. 4, 3’5 ; pm. 3, 3‘2 ; pin. 2, 3‘4. C. 8116. Anterior ])ortion of skull of a young individual with the milk-molars 2-4 (?) in sitn. This specimen shows the form and position of the nasal o[)ening. Figured on PI. XI 11. The dimensions (in centimetres) of this specimen are: — Total length of specimen 24'5 Length from tip of nasals to end of snout 13-4 „ „ anterior rim of orbit to end of snout .... 13 Distance between the jiostorbital processes of the jugal and frontal 4-5 Width of skull-roof at ])ostorbilal jjrocesses 14 Greatest width of nasals 6'4 PAL.-KOiAIASTODON BEADNEMA. 155 Tlio dimensions (in centimetres) of tlie teetli are: — Length. Width. mm. 2 t3'4 I'l mm. 2-9 2 mm. 4 4 2 3 M. 8542. Plaster cast of tlie above sftecimen. ]\fade in the Jiritisk MuseuDi. C. 7890. Eight maxilla with base of zygomtt. Chiefly remarkable for the large size of pm. 3. Tin* lengths of the teeth are : — pm. 3, 3'7 cm. ; pm. 4, S’o cm. ; m. 1, 4 8 cm. ; m. 2, t)’2 cm. C. 9296. Eight maxilla with the molars ; m. 3 greatly worn. Lengths : — m. 1, 3’7 cm. ; m. 2, 4‘7 cm. ; m. 3, 5'3 cm. C. 7837. Portion of an upper incisor tusk of large size. At base the long diameter is G cm., the short 3’0 cm. C. 8981. Upper incisor tusk with a slight spiral twist and a hand of enamel on outer face. This specimen is nearly complete. Length in straight line 25'3 cm. ; length along curve 28 cm. C. 8467. Upper incisor tusk : slight spiral twist, enamel lost. Imperfect, length preserved 18 3 cm. in straight line. M. 8417. Upper incisor tusk with a slight spiral twist and a hand of enamel on outer face. Length (so far as preserved) IG‘5 cm. ; long diameter near base 4’7 cm., short diameter near base 2’G cm. M. 8417 a. T erminal portion of large upper tusk. Enamel band on outer side, w'car-surface on lower side of tip. Length 15 cm. ; long diameter at widest part 5'2 cm., short diameter at widest part 3‘5 cm. M. 8483. Portion of base of lower incisor, cut to show internal structure. Presented by IT'. E. de Winton, Esq., 1903. C. 9305, C. 9307. Two right upper premolars. C. 8488. Left upper premolar. M. 8845. Two right up[)er second premolars. Presented by the Egyptian Government, 1904. M. 8419. Left upper second premolar. C. 8479. Eight upper third premolar. Length 3'G cm. C. 8964. Eight upper third premolar. Length 3‘1 cm. M. 8419 a. Left upper third premolar. C. 8101, C. 8474, C. 8487. Three right upper fourth premolars. M. 8419 b, M. 8845 a (two). Three left upper fourth premolars. M. 8850. Fra gment of left maxilla with qnn, 3 and 4. The lengths of the teeth are 3‘3 cm. and 3'5 cm. respectively. Presented by the Egyptian Government, 1904. M. 8851. F ragment of right maxilla with pm. 4 and m. 1. Lengths 3'3 cm. and 4'4 cm. respectively. Presented by the Egyptian Government, 1904. M. 8480. Fragment of right maxilla with m. 1 and m. 2. Lengths 4’1 cm. and 5'8 cm. respectively. l^resented by IT'. E. de Winton, Esq., 1903. x2 .150 TEliTIAlir YEHTEBIIATA OF THE EATOm. C. 8954. Loft, Tippor first jiiolar, iiincli worn. C. 8101. Two riolit uj)])<>r scn-ond molars. M.8481. lioft uji|)('r second molar. Presented hy IF. E. de Winton, Es'/.. 190:5. M. 8418 a. Riaht and left upper second molars. M. 8418. Three njiper third molars. C. 8965. 1 jet't iii>per third molar. C. 8489, C. 9291. Right upper third molars. M. 8420. ? Upper third molars. M. 8847. Lett upper third molar. Presented hy the Egyptian Government, 1901. M. 8418 b. Portion of maxilla with m. 3 and part of /a. 2. M. 9122. Posterior portion of right ramus of mandible with m. 3. The dimensions (in centimetres) are : — Height at coronoid process . . ,, cond3de Width of a.scending ramus . . Length of m. 3 Width of )H. 3 M. 8494. Atlas vertebra. Width of articulation for skull . 21-5 ]9r> S-7 5-2 I’resented hy IF. E. de Winton, Esq., 1903. 17 cm., app. 14'4 cm. Presented by IF. E. de }Vinton, Esq., 190.'). The following vertehraj may belong M. 8840. C lervical vertebra. M. 8389. Cervical vertebra. M. 8390. Lumbar vertebra. M. 8842. laimbar vertebra. C. 9115. First thoracic vertebra. C. 9235. Anterior thoracic vertebra. C. 8084. Anterior thoracic vertebra. C. 8275. Centrum of lumbar vertebra. to Pala;omaslodon : — Id resented hy the Egyqdian G ocerninenf , 1904. Presented hy the Egyptian Government , 1902. J'resented hy the Egyptian (jorernment , 1902. Presented hy the Egyptian Government, I'dOl. FalaBomastodon wintoni, Andrews. [Text-figs. 50 15, 5-3, 54.] 1905. Paloeomastodon wintoni, C. W . Andrews, (h'ol. Mag. [5] vol. ii. ]>. 5)i:5. Type Specinien. — A rnandible wanting the angrdar region and the anterior cheek- teeth (text-fig. 53) ; British Museum. A fine mandible in Cairo, in uhieh tiu' PA )M A S'1’0 DON AVI NT( )N[ . 157 incisors arc wanting but which is othcn-wise nearly complete (text-fig. 54), may be regarded as a co-type. 'I'his species differs from P. headnelli in (1) its somewhat smaller size; (2) the extension backwards of the symphysis so that its posterior border is only just in front of pm. 3 ; (3) the position of the mental foramen on the side of the symphysis instead of behind it ; (4) the greater complication of the molars and their greater length in proportion to the width, the last lower molar (text-fig. 50 B) consisting of three transverse crests and a distinct talon. From P. minor and P. parims this species is easily distinguished by its larger size and the difference of its last lower molar (see text-fig. 50). P. ivintoni seems to be by far the commonest species, and probably the greater number of specimens above referred provisionally to P. headnelli belong here. This Text-fig. 53. Mandible of Pcilceomastodon wintoni, type specimen, from abo\ e. cond., condyle; cor., coronoid process ; d.c., dental canal ; incisoi’. The premolars and first molar on the left side have been restored from another specimen, i nat. size. remark particularly applies to the skulls and upper teeth, which, in the absence of associated skulls and mandibles, cannot be determined with certainty ; though the absence of any mandibles of the type of P. headnelli from the pits in which most of these specimens were collected is strong presumptive evidence that they do not belong to that species, but to the present one, to which all or nearly all the mandibles and lower teeth are referable. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. M. 8414. Mandible wanting the angular region and the cheek-teeth in front of m. 2. Type specimen figured (text-figs. 50 B, 53). The incisors are preserved ; they are procumbent and spatulate teeth terminating in a point ; their width at the base is 5’2 cm., the length TEETIAKY VERTEEllATA OE THE FAYCM. ]-')S aloiiff ilicir inodiaii border is in. 3 2' 7 1’7 2)w.4 3-7 2-4 m. ] 3‘o 2’8 9H. 2 5‘7 3’r> VI. 3 7 4-f C. 8457. Nearly jterfect mandible of a somewhat smaller individual than either M. 8414 or (h 847)1), the whole jaw being rather more .slender. The dimemsions (in centimetres) are : — Length from condyle to tip of symphysis 34 „ from atigle to tip of sympliysis (il) „ of symphysis 22-() „ of posterior end of vi. 3 to tip of .symphysis .... 47'5 AVidth of sympliysial region at narrowest 5-.') The dimensions (in centimetres) of the teeth are : — Lengtli. Width, ]m. 3 2-9 1 '4 pm. 4 8’.j 2 VI. 1 2~) VI. 2 ,5-4 3-1 VI, 3 (id) 3-5 M. 8384. Mtindihle of small individual. The ttngular region is imperfect, and the symphvsis is much broken. The dimensions (in centimetres) are: — Approximate length from condyle to tip of symphysis ,, of sympliysis (>4 22 PAL^OMASTODON WrNTONL 1-50 The dimensions (in centimetres) of the teeth are : — Length. Widtli. jm. 3 3 1’8 pm. 4 3-9 24; m. 1 4-1 2-8 771. 2 5‘0 3'3 777. 3 G4) 4 J^resenied by the Fjjijptian (Hoi'ernment, 1902* Text-fig. 54. Mandible of Palceomastodon luintoni : A, from above ; B, from left side. cond., condyle ; cor., coronoid process ; i., alveolus of incisor ; m.f., mental foramen. nat. size. M. 8415. Portions of right and left rami of mandible of a young individual in which ni. 3 had not been cut. The dimensions (in centimetres) of the teeth present are : — Length. Width. ^7777. 3 3’7 pm. 4 4'6 777. 1 5 3 777. 2 G o 4-2 M. 8853. Portion of left ramus of mandible with the cheek-teeth in excellent preservation. IGO TKIiTIAlIV VERTEBKATA OE THE EATUM. Tho poster ior end of Uie synipliysi.s is l)etAveen 2 and B cm. in front of the anterior end oi tlio tootli-sei-ies. TlnMlimensions (in centimetres) of the teeth are: — Length. Width, 1-7 2-4 4-1 2-8 5-.5 3-5 7‘3 4-] I’rcsented htj the Egypt, ian Goveniinenf, 1904. M. 8854. Portion of right ramns of mandible with o— 4 and /». 1-2 in excellent preservation. The dimensions (in centimetres) of these teeth are : — Length. Widtli, 3-3 1-7 2-0 4-1 2-8 5-5 3-4 Presented hy the Egyptian Government,, 1904. M. 8464. Portion of right ramns of mandible with pw. 4 and m. 1. The lengths of these teeth are 3'8 cm. and 4'3 cm. respectively. l*resented by TP. E. de Winton, Esq., 1903. M. 8416. Left lower molars and premolars. Length of m. 3, 7'5 cm. M. 8420. Right lower third molar. Length 6'9 cm. M. 8481. Right lower third molar. Length cm. Presented hy IE. E. de Winton, Esq., 1903. M. 8849a. Left lower third molar. Length G'5 cm. Presented hy the Egyptian Government, 1904. M. 8849b. A large lower third molar of peculiar type. The whole tooth is broad ; the intermediate tubercles are well developed and each of the main cusps forming the two hiiuler crests is partly divided into two tubercles. This specimen may indicate the existence of another as yet undescribed species. Length 8‘2 cm., width 4'8 cm. Presented hy the Egyptian Government , 1904. The following may be referred to the present s[)ecies, but possibly some may belong to /'. l>eadnelli : — C. 7841. Right ramus of mandible, complete ])Osteriorly. The lengths of the teeth are: pni.'.], 3’3cm.; ‘p}n.4:, 4’2 cm. ; /a. 1, 4d) cm.(?); m. 2, (i’l cm.; /«. 3, 7‘3 cm. C. 7839. Left ramus of mandible. The lengths of (he teeth are : you. 3, 3‘1 cm. ; pm.\, 3'4 cm.; m. 1, 3'9 cm. ; m. 2, ;V3 cm. ; m. 3, 7'3 cm. C. 9294. Left ramus of immature mandihhu The lengths of the teeth are : /an. 3, 2‘9 cm. ; pm. \, 3'3 cm.; w. 1, 3‘7 cm.; ni.’l, o'l cm. Left ramus of immature mandil)lc with pm. 3-4 aud m. 1-2. Left ramus of immature mandilde with m. 1-2, tho latter just cut. M. 1, U'O cm. long. Right ramus of an immature individual with pm. 3-4 and m. 1-2 in. sitn, m. 3 as germ a(. back of jaw. The lengths of the t(‘eth are: pm.?), 3’3 cm. ; pm. I, 4'0 cm.; m.\, f)’! cm.; tn. 2, 4‘() cm. C. 7848. C. 7835. C. 7333. rAL^OMASTODON WINTONI. IGl C. 8914. Anterior portion of mandibular sympliysis with incisors in silu. Greatest width between tlie outer ed^es of the alveoli ... 10 cm. AV^idth of each incisor 4'5 „ Length protruded from alveolus G‘2 „ M. 8478. Symphysial region of mandible with incisors of a large individual. Figured on PL XIV. fig. .3 as P. headnelli. Length of symphysis 27 cm. AVidth of symphysis at narrowest 8'5 ,, app. ,, the two incisors 11'5 „ Length of outer side of incisors 20 „ ,, inner side of incisors 14 „ Presented Jnj IF. E. de Winton, Esg., 1903. C. 8468. Right lower incisor. The wear-surface extends both on the upper and lower side of the tooth for about 5 cm. The ventral face is enamel-covered ; the surface of the dentine is marked by straight longitudinal grooves. Width 4‘3 cm. ; length (so far as pre- served) 17'0 cm. C. 9214. Large left lower incisor. Ventral face covered with enamel ; also a very thin covering on upper surface. The dentine core is marked by broad, shallow', longitudinal grooves. AA^idth 7'5 cm. M. 8385. Imperfect left incisor, showing wear-surface. Width 4'5 cm. Presented by the Egyptian Government, 1902. M. 8848a. Left low'er third premolar. Presented by the Egyptian Government, 1904. C. 8470, C. 8963, C. 8971, C. 9304. Lower third premolars. M. 8848b. Left lower fourth premolar. Presented by the Egyptian Government, 1904. C. 8472, C. 8492, C. 9279, C. 9303. Lower fourth premolars. C. 9301-2. Right and left lower first molars. Length 4'2 cm. C. 9289. Right lower first molar. Length 4 cm. M. 8846. Left lower second molar. Length 5‘8 cm. Presented by the Egyptian Government, 1904. M. 8420, M. 8481. Low'er second molars. Presented by IF. E. de Wintoji, Esq., 1903. M. 8479 a. Portion of mandible with second molar. Presented by IF. Id. de Winton, Esq., 1903. C. 9292. Left lower second molar. Length 5'7 cm. C. 9298. Right lower second molar. Length G'O cm. C. 9299, C. 9300. Right and left lower third molars. Length 7'2 cm. M. 8482. Last lower milk-molar. Length 4'2 cm. ; width 1'9 cm. Presented by IF. E. de Winton, Esq., 1903. The following vertebrm may be referred provisionally to P. wintoni : — C. 9094. Atlas vertebra. C. 9074. Atlas vertebra. C. 8261, C. 8266, C. 8315. Atlas vertebrae. M. 8856 a, b. Two atlas vertebrae. Presented by the Egyptian Government, 1904. Y IG2 TERTIARY VERTEBRATA OF THE EATCtM. Tho dimensions (in centimetres) of some of the above specimens are : — Width between outer edges of articulation C. 9094. C. 9074. C. 8201. C. 8315. M.8856 a. M. 8850 6. for skull 15-5 15-5 16 15-7 15-3 15 „ of surfaces for axis 13-5 12 13 12 12 12 ,, to ends of transverse processes . . 25-7 25 app. 26-4 25-4 C. 8079. Nearly complete axis vertebra. This specimen shows the large peg-like, somewhat compressed odontoid with distinct ventral facet, the strong hypapophysial ridge, the very high neural arch with the neural spine deeply hollowed out posteriorly by a deep fossa for the attachment of ligaments. M. 9123. Atlas vertebra similar to last, but less nearly complete. M. 8857. Imperfect centrum of smaller axis. Presented by the Egyptian Government, 1904. The dimensions (in centimetres) of the above axis vertebrse are : — C. 8079. M.9123. M. 8857. liength of centrum with odontoid . 12-5 12 app. 9-5 Width of surface for atlas .... 11 app. 11 app. 10 „ posterior face of centrum . 7'5 app. 8 Height to top of neural spine . . . . 14 + 15-5 „ of neural canal 3 3’5 app. M. 8513. Right astragalus. Figured in text-fig. 52. The dimensions (in centimetres) are : — Width of tibial surface, including facet for internal malleolus .... 8 ,. calcaneal surfaces 8 „ navicular surface 7’7 Presented by IF. E. de Winton, Esg., 1903. C. 8355. Portion of left astragalus. C. 10063. Imperfect left calcaneum. Palaeomastodon parvus, Andrews. [Text-figs. 50 C, 55-59.] 1905. Pakeomastodon parvus, C. W. Andrews, Geol. Mag. [5] vol. ii. p. 5G2. Type Specimen. — Imperfect right ramus of mandible, with pm. 3-4 and m. 1-3 in .situ, (text-fig. 55) ; British Museum. This species is distinguished from P. headnelli by its small size, but at the same time it approaches that species very nearly in the comparative simplicity of its teeth, ])articularly in the form of m. 3, and in having the posterior end of the mandibular symphysis some distance in advance of the anterior ])remolar, a character which at once distinguishes it from P. wintoni. The third molar (text-figs. 50 C, 55) consists of two transverse ridges, each composed of two tubercles, and a small third ridge consisting PAL^EOMASTODON PARVUS. 163 of a larger outer and a smaller inner tubercle ; there is a small intermediate tubercle in the anterior valley, but otherwise accessory tirbercles are wanting ; the enamel is very smooth and the cingulum practically absent. M. 2 is trilophodont, but the last ridge is much smaller than the others ; it consists of an outer larger and a smaller inner cusp. So far as their molar pattern is concerned, both this species and P. headnelli seem to be more primitive than P. ivintoni ; but, on the other hand, P. headnelli by its larger size, and both it and the present species in the elongation of the mandibular rami, seem to be somewhat more specialized. This intermingling of primitive and more specialized characters is to be expected in a group represented by several Text-fig. 55. Right ramus of maudible of Palceomastodon parvus. Type specimen. About 1 nat. size. contemporary species and undergoing rapid change in a given direction, the final product, in this instance Tetrahelodon or some closely similar form, being the resultant of the various modifications, and in this case combining increased length of the mandible with more complicated molar structure. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. M. 8479 a. Right mandibular ramus, imperfect at both ends: pm. 3 & 4 are greatly crushed and TO. 1-3 much worn. Type specimen figured (text- figs. 50 C, 55) . The mental foramen is beneath the anterior end ofpm. 3, and the posterior end of the symphysis is about 5' 5 cm. in front of that point. The dimensions of the teeth are given in the table on page 169. The depth of the mandibular ramus beneath to. 2 is 7‘2 cm., in front oi' pm. 3 6’6 cm. Presented hy Tl'. E. de Winton, Esq., 1903. M. 8847. Almost unworn third lower molar. Presented hy the Egyptian Government, 1904. M. 8846. Right upper molar (? second) almost certainly belonging to this species. Presented hy the Egyptian Government, 1904. Probably several of the smaller teeth and jaws in Cairo may belong to this species, but further examination of the material there would be necessary to determine this. Y 2 104 TEETIAEY VEETEBEATA OF THE FATCtM. Tho humerus, ulna, and tibia enumerated below, together with some small astragali similar to that described above (p. 1-19) and figured in text-fig. 52, probably belong to this species or to P. minor. C. 8881. Right humerus with its upper part much crushed (text-fig. 50). This specimen differs more from the humerus of the later Proboscideans than does the humerus of P. headnelli described above. The large rounded head {h.) is abruptly truncated on the inner side by the flat inner face of the upper part of the shaft. Anteriorly it bears a small “ lesser ” Text-fig. 56. Eight humerus of Palaomastodon {‘1) i^arvus : A, from front ; B, from inner side. If.g., bicipital groove ; c./., coronoid fossa ; d., deltoid crest ; g.t., greater tuberosity ; /t., Iiead ; hr., inner condyle ; hi., lesser tuberosity ; o.c., outer condyle ; s.r., supinator ridge ; tr.i., inner part of trochlea ; ir.o., outer part of trochlea. 5 nat. size. tuberosity (/.h), which is separated by a deeply concave bici])ital groove (5.y.) from the greater tuberosity (ff-t.), which is very large and rises considerably above the head ; from it a ridge forming tho outer edge of the bicipital groove runs down tho anterior face of the upper third of the shaft. It is diflicult to determine the exact form of the upper portion of the shaft owing to the crushing it has undergone, but it can be PALiEOMASTODON PARVUS. 1G5 M. 8889. C. 8063. M. 8890. seen that the deltoid ridge (d.) formed a prominent ohlicpie crest continued np to tlic greater tuberosity. The coronoid fossa (c.f.) is wide and moderately deeply concave; the olecranon fossa is large and deep, particularly on the outer side. The outer and inner (i.c. and o.c.) condyles are both fairly prominent, the latter projecting consideraldy backwards. The supinator ridge (s.r.) is short, much shorter relatively than in the humerus of F. headnelli dcscril)ed above. The articular surface is divided by a broad groove into an inner larger (fr.L) and an outer smaller portion (tr.o.). The former bears a slight ridge which marks the separation of the surface for the radius from that for the inner portion of the ulna. The bone, as a whole, is very thin-walled and lightly built — a circumstance that may account for the extreme rarity of bones of Palceomastodon. The chief points by which this humerus differs from that of Eleplias are : (1) the greater tuberosity is larger and rises more above the head ; (2) the supinator ridge is very much smaller, so that the distal portion of the bone is less expanded. Plaster cast of the above specimen. A similar right humerus wanting the proximal end. Plaster cast of the above specimen. Made in the British Museum. Made in the British. Museum. The dimensions (in centimetres) of the above humeri are : — C. 8881. C. 8063. Length . . . 45-2 43-3 -f Width of head ... 9 . . „ of shaft at narrowest . . . ... 5-7 5*4 „ lower end at widest . . . . . . 13-8 13 + „ distal articulation .... ... 9-8 10 C. 8028. Nearly complete right ulna (text-fig. 57) . The olecranon (pi. ) is large, greatly expanded at the end, and projecting strongly towards the inner side ; it does not rise above the upper angle of the articulation. This latter is triradiate in form ; the upper lobe projects strongly forwards, while of the lower two, the outer has a straight anterior border, beneath which is the elongated facet (r.s.) for the upper end of the radius; the inner is oval in outline and seems to have little or no contact with the radius. The whole shaft of the bone is curved backwards ; it is triangular in section, the anterior face being deeply' concave from side to side near its upper end (r.g.) Distally it widens out somewhat, but the epiphysis having been lost, the distal articulation cannot be described. The whole ulna is practically that of a miniature elephant. The dimensions (in centimetres) of the specimen are : — Length (without epiphysis) 38 Width of articulation for humerus 9 3 „ middle of shaft 4’8 M. 8891. Plaster cast of the above specimen. Made in the British Museum. II. 8858. Upper end of left ulna. Presented by the Egyptian Government, 1904. C. 8883. Right tibia (text-fig. 58). In form this bone is almost exactly similar to the tibia of P. headnelli figured on PI. XVI. fig. 4. In the proximal articulation the inner facet (i.) 166 TERTIARY VERTEERATA OF THE FAY()M. is the larger and is widest from before backwards ; at its antero-external angle it runs up on to the prominent intercondylar process (ic.p.), on the outer side of which there is a deep fossa for the attachment of ligament. The outer facet (o.) is widest from side to side, and beneath its outer edge there is a flattened surface, apparently for the upper end of the fibula. The upper part of the not very prominent cnemial crest (cn.) is divided into two by a deep depression, the outer portion being the largest. The middle portion of the shaft is flattened behind and convex in front; towards the distal articulation it widens out and bears on its postero-internal surface a prominence (p.) forming the outer side of a groove, precisely similar to that seen in the tibia of P. headnelli. The distal articulation is also like that found in the large species ' there is a prominent internal malleolus (i.m.) bearing an astragalar facet looking outwards and forwards ; external to Text-fig. 57. Right ulnca of Palaomastodon {^)parvus\ A, from front; B, from inner side. oh, olecranon process ; rp., radial groove; r.s., radial surface. | nat. size. this is the main surface for the astragalus (a.s.), strongly concave from before backwards, and is produced downwards into a blunt ])oint both lad'ore and behind. External to this surface there is a roughened facet (/.) looking downwards and outwards, apparently for articulation with the fibula. The chief dithu'ence between this tibia and that of h'lejihas is in the form of the di.stal articulation. In the recent form, probably owing to the increasing size and weight, the astragalar surface is much broader and more gamtly concave, and this increase of width has led to the reduction of the internal malleolus to a mere blunt jjoiut. Otherwise the two tibias are very similar even in small points. PALJiOMASTODON PAllVUS. 167 These remarks apply likewise to the tibia of P. headnelli. The dimensions (in centimetres) of this bone are : — Extreme length 38'8 Width of proximal articulation (for astragalus only) . . . . 11'5 „ middle of shaft 5’3 ,, distal articulation 6 The length of the tibia of P. headnelli is 63’5. O Text-fig. 58. Right tibia of Palceomastodon (^) parvus : A, from front ; B, proximal end ; C, distal end. as., surface for astragalus ; cw., cnemial crest ; /., /.', surfaces for fibula ; surface for inner condyle of femur ; ic.j)., intercondylar process ; i.m., internal malleolus ; o., surface for outer condyle of femur ; p., internal distal prominence. 5 nat. size. Text-fig. 59. Left astragalus of Palceomastodon (?) parvus : A, from above ; B, from below. ect., ectal facet ; i.m., surface for internal malleolus of tibia; nav., navicular facet ; sus., sustentacular facet; tib.j tibial facet. |- nat. size. IGS TEllTIAliY VP:KTEBEATA OF THE EATtjM. M. 8892. Plaster cast of the above specimen. Made in the British Museum. C. 8016. Immature left til)ia, imperfect at ends. C. 9221. Immature rit^bt tibia, rather smaller than last, imperfect at ends. C. 8334. Left astragalus, the proximal articulation of which agrees with the distal articulation of ilie tibia just described. This bone is figured (text-fig. 59) and is very similar to that described above (p. 149) and figured (text-fig. 52). It is chiefly remarkable for the prominence of the knob forming its postero-internal angle. The dimensions (in centimetres) are : — Width of tibial surface, including facet for internal malleolus . 5'8 „ calcaneal surfaces 5-G „ navicular surface 5 M. 9237. Plaster cast of the above specimen. Made in the Jiritish M^lseum. C. 8636. Left astragalus, similar to last. II. 8406. Left astragalus, similar to last. Palseomastodon minor, Andrews. [Plate XIV. figs. 1, 1 a; and text-fig. 50 D.] 1904. P alccomastodon minor, C. W. Andrews, Geol. Mag. [5] vol. i. p. 115. Type Specimen. — Portion of the right ramus of the mandible of a young individual (PI. XIV. figs. 1, I a) ; British Museum. This species is not only much smaller than P. headnelli and P. wintoni, but differs in the structure of its molars, particularly of m. 3. This tooth is long in proportion to its width ; it consists of three complete transverse main crests and a small talon- like fourth ridge consisting of several small cusps. The anterior crest is composed of two large cusps, the outer of which is connected with a small accessory tubercle partly filling the first valley. The second and third crests consist of two main cusps, each partly divided into two transversely arranged tubercles ; there is no tubercle in the posterior main valley ; the whole tooth is more clearly lophodont than in the other species. This tooth is easily distinguishable from the last molar of /b which consists of only two crests and a talon, which is composed of two large cusps (see text-fig. 50 C). ]\I. 1 and m. 2 are both trilophodont ; the antero-external cusp in each is connected posteriorly with a small cusp in the anterior valley ; the second outer cusp is distinctly divided into two tubercles, especially in m. 2. Pm. 4 is bilophodont, pm. 3 a simple compressed cone with small anterior and })Osterior cingular l idges. The length of the symphysis is unknown. Form. d‘ Loc. — Fluvio-marine beds (U})per Eocene) : north of Ihrket-el-Qurun. PAL.EOMASTODON MINOK PIIIOMIA . 1G9 M. 8479b, Kioht ramus o£ maiulible, imperfect at both ends. Fm. 3, pm, 4, m. 1-3 are present, m. 3 as an uncut germ; pm.\-m.2 are somewhat imperfect on the inner side. Typo specimen descril)ed in Geol. Mag. [5] vol. i. (1904) p. 11.5. Figured on PI. XIV. figs. 1, 1 A ; also tlie second and third molars in text-fig. 50, D. The dimensions (in centimetres) of the teeth are : — Length. Width. pm.^ 2 8 1-0 2-G 2 app. m.\ 3'2 2'1 app. m. 2 4-5 2‘9 app. w. 3 4-8 2-9 Tlie lengths (in centimetres) of the teeth compared with those of the other species are shown in the following table : — P. minor. P. parvus. P. wintoni. P. beadnelli. 2-8 3-5 app. 3 4-1 app. 2-0 3-5 app. 3-5 4-8 3-2 3-8 4-3 4-8 4-5 4*5 5-7 6-5 4-8 4-6 7-3 7-8 Length of molar series 12-6 13 17-2 19-4 ,, premolar series .... 5-7 7 app. 63 9'2 app „ molar and premolar series . 18 19-7 23 28-5 Presentpd by W. E. de Winton, Esq., 1903. The following specimens may be referred pro\dsionally to this species : — C. 8110. Two trilophodont upper molars. These teeth are of the size and type that might be expected in the upper jaw of this species. Length 4’5 cm. ; width 3'1 cm. M. 8860. Atlas vertebra. AVidth of articulation for skull 12-8 cm. Genus PHIOMIA, Andrews Beadnell. [A Preliminary Note on some new Mammals from the Upper Eocene of Egypt, pp. 1-5, figs. 1, 2 (Survey Department, Cairo, 1902).] Known only from an imperfect mandibular ramus, in which the single spatulate incisor is serrated on its outer margin. It was originally suggested that this mandible might represent a very aberrant type of Creodont, but this determination is certainly wrong, Schlosser * has suggested that the specimen in question is the anterior portion of the mandible of a very young Palceornastodon, a supposition which not impossibly may be correct, though since this is by no means certain it seems preferable to keep the genus Fhiomia for the present and place it in its present position. * Neues Jahrb. £. Min. Geol. u. Palaeont. 1905, vol. i. pt. i. (Eeferate) p. 157. z 170 TEETFAliY VEliTEBEATA OF THE EAYCM. Plliomia serridens, Andrews Sc Bcadnell. [Plate XVJII. figs. 4, 4 a.] 1902. Pltiomm serridens, Andrews & Eeadnell, A Pi-eliniinary Note on some new Mammals from the Upper Eocene of Egy})t, ])p. 1-5, figs. 1, 2 (Survey Dept., Cairo). 1005. Falwomaslodon, juv^, Sclilosser, Neues Jahrb. £. Mineralogie, etc. vol. i. pt. i. (Referate) p. 157. Type Specimen. — Anterior portion of left ramus of mandible Avitli incisor and two cheek-teeth, figured and described loc. cit. supra, also PI. XVIII. figs. 4, 4 a ; Geological Museum, Cairo. 4'he type and only known species, with mandibular symphysis G'5 cm. in length. Form. & Log. — Fluvio-marine beds (Upper Eocene): north of Birket-el-Qurun. The mandibular ramus (PI. XVIII. figs. 4, 4 a) upon winch the species is founded is incomplete posteriorly. The symphysial region {sym.) is very long and deepens consider- ably from before backwards ; the upper surface with its fellow of the opposite side must have formed a spout-like groove, while the ventral surface is strongly convex from side to side and to some extent also from before backwards. Behind the symphysis the ramus of the jaw arches outwards, its outer surface being convex from before back- wards and also from above downwards ; the inner surface is concave in the former direction and nearly flat in the latter. There are two foramina on the outer face: one, the larger of the two, is just behind the socket of the incisor ; the other is beneath the anterior end of the second of the cheek-teeth in situ. The bone shows traces of the peculiar fibrous appearance characteristic of many young bones, a circumstance which tends to support Schlosser’s view as to the nature of the specimen. The incisor [i. I) is of very peculiar form. Its inner border, where it is in contact with its fellow of the opposite side, is straight. The outer edge is conve.v in front and is marked by a series of crenulations (about five in number). The upper face of the tooth is concave from side to side, the ventral convex with two or three sliglR longitudinal ridges. The tooth thickens rapidly towards its base. The enamel covering is confined to the end of the crown; it is found on both the upper and lower surface ; on the outer side it extends back as far as the last of the denticulations, and on the inner not quite so far. The incisors must have formed a S])out-like continuation of the symphysis, much as in Fahvomastudon. The great size and increase in thickness of these teeth towards their base make it difhcult to regard them as belonging to the milk-series ; on the other hand, if they are the permanent incisors, they could never have attained the size of those of ]\ila'omastodon hcadneUi or winfoni, so that if this animal was a Palceomastudon it must have been quite a small species. PIirOMFA SERHIDENS. 171 TJchind the incisors there is a loii" sharp-edged diastema about 5’5 cm. in lengtli. d'he first cheek-tooth is small atul laterally compressed, with a high anterior cus]), slightly bifid at the summit, and a smaller posterior one, which seems to belong to the cingulum ; there is also a slight cingular prominence on the front of the tooth. The next tooth is large and complex. The anterior half consists of three cusps; one anterior, with a small stylid closely \inited to it in front ; the other two arranged transversely. There is a small accessory tubercle on the posterior slope of the outer of the two cusps. This anterior portion of the tooth is separated from the wider posterior part by a deep valley, behind which there arc two large and closely united cusps arranged transversely and a small accessory posterior tubercle. The nature of these two cheek-teeth is open to some doubt ; probably they are deciduous molars, though this is not absolutely certain, and although the jaw has been carefully cut away beneath the larger tooth no trace of any germ of the replacing tooth can be seen. On the whole, it seems that Schlosser is possibly right in his surmise as to the nature of this specimen, and it may be considered as having belonged to a young individual perhaps of one of the smaller species of Falmomadodon ; but since it is very small and there is some doubt as to the nature of the teeth, the generic name Phiomia may be retained till further material is available. C. 10007. Anterior portion of left mandibular ramus, with incisor and two cheek-teeth. Type specimen described and figured, loc. cit. ; also Tl. XVIII. figs. 4, 4 a. The dimensions (in centimetres) of this specimen are : — Extreme length of specimen, so far as preserved 14’2 Length of protruded portion of incisor, measured along median border 3 app. AVidth of incisor at alveolus 1’6 Length of symph)sis 6’5 Greatest depth of symphysis 2 Length of diastema between incisor and first cheek-tooth . . 6 app. Depth of ramus beneath second cheek-tooth 3'5 Length of first cheek-tooth 1-2 AVidth of first cheek-tooth ‘5 Length of second cheek-tooth 2'7 AVidth of second cheek-tooth 1'3 M. 8193. Plaster cast of the above specimen. Made in the British Museum. 172 TERTIAET VERTEBRATA OF THE FAYtTM. I N c: E R T S E D I S. Family BARYTHERIIUyE. This family is known only from a single genus, Banjtherium, the characters of which are given below. Its systematic position is still very doubtful and it does not fall within the limits of any of the suborders as at present defined. In a former ])a])er * it was suggested that possibly it may he found to constitute a subdivision of the Amhlypoda, which would be of the same rank as the Dinocerata and might he called the Barytheria. Genus BARYTHERIUM, Andrews. [‘ Nature,’ Oct. lOtli, 1901, vol. Ixiv. p. 577; also Geol. Mag. [4] vol. viii.(1901) p. 52m. 3 4'3 4'7 j>m. 4 .5'7 S'.'j m.l 5'7 m.2 84) 6-4 m. 3 10-5 7 Total length of upper molar and premolar series 36‘5 „ „ lower molar and premolar series 38 5 app. Mandible (PI. XVII. fig. 5): Length of mandible so far as preserved GG Depth of ramus beneath -pm. 4 25'5 Length of symphysis 38‘4 Height to top of coronoid process 3G Scapula (PI. XVII. figs. 9, 9 a) : Length so far as preserved 48 Width of glenoid cavity 13 Distance in straight line between posterior edge of glenoid cavity and end of coracoid process 18 Width of neck of bone 17 Humerus : Length G0'4app. Width of distal articular surface IG'5 Radius (PI. XVII. figs. 8, 8 a) : Length 42 '5 Width of proximal articulation (side to side) 11'5 „ „ „ (before backwards) .... G „ shaft at narrowest point 5'5 „ distal end 11 app. M. 8054. Plaster cast of left maxilla and teeth described above. Made in the British Museum. M. 8055. Plaster cast of mandible and teeth described above. Made in the British Museum. M. 8057-8. Plaster casts of the radius and scapula described above. Made in the British. Museiim. C. 10012 a. Left humerus, wanting proximal end. This specimen is described above and figured on PI. XVII. figs. 7, 7 A. The dimensions (in centimeti’es) are : — Length so far as pi’eserved 5G E.xtreme width at condyles 29 Width of distal articulation 14 app. „ shaft at narrowest point 11'2 „ „ deltoid crest 17’7 M. 8056. Plaster cast of the above. M. 9125. Proximal end of a right femur. Diameter of head . . . . Greatest width of upper end Made in the Briti.sh Museum. . . 10'2 cm. app. . . 22 cm. 2a 178 TEirJ'lAEY VEUTBBEATA OF THE EAY&M. Suborder ARTIOBACTY LA. Family ANTHRACOTIIEFIIIFF:. Genus ANCODON, Pomel. [Arcliiv. Sci. Pliys. et Nat., Geiiive, [4] vol. v. p. 207 (Juno 1847) (as a subgenus of Palaotliervum.)~\ 1848*. Bothrioclon, Ayniard, Ann. Soc. Agile. Sci., Arts, et Comm, du Puy, vol. xii. pp. 239, 246-247, footnote (as a subgenus of Aiitliracotlieriuin'). 1848. I]yo-potamus'\, Owen, Quart. Journ. Geol. Soc. vol. iv. ]). 103. 1848. Ancodusi, Pomel, op. cit. supra, [4] vol. viii. pp. 324-.5 (raised to generic I’ank, and unnecessarily emended from Ancodon'). At least two species referable to this genus occur in the Upper Eocene beds of the Fayum, and from the comparative abundance of their remains these animals seem to have been very common in the later Eocene period. As might be expected from their somewhat earlier date, the sjiecies here described are rather more primitive in their tooth-structure than are the forms from the Oligocene of Europe and America. Tliis is especially noticeable in the more brachyodont and less selenodont character of the molars, which resemble to some extent those of Anthracotherium, but are still more like those of the much later (L. Miocene) genus Braehyodas, remains of which, it is interesting to note, have been found at Moghara, to the north-west of the Fayum. It may eventually be necessary to separate the present species from Ancodon, but on account of the great general resemblance of the lower jaw of yi. to that of some of the European forms such as A. velaiinus, it seems desirable, until a more distinctive character than the slight differences in the teeth above referred to has been found, to retain the same generic name for both. The skeleton in this genus has been described in detail by Kowalevsky [j;, Filhol §, Scott II , and others, so that here it will only be necessary to give a short account of the various specimens in the collection under their several numbers in the list below. * There i.s some doubt about tins date, since while the titlepage of the volume is dated 1846, the cover has 1848. lu spite of the fact that it has been authoritatively slated (see Bush, Amer. .lourn. Sci. [4J vol. xvi. (1903) pp. 97-98) that this volume was printed in 1847, it seems jn-obable that the date on the cover represeuts the date of issue (i. e. of publicatiou), particularly as the author’s sepai'ate copies are known to have been dated 1848 also. This being the case, it seems desirable to ado2)t Boniersname Ancodon of 1847 for the genus. t J’reoccupied in 1844 by Kaup for a genus of lIippo()otamidic. X “On tlie Osteology of the llyopotamidye,” Idiil. Trans. 1873, p. 19. § “ Etudes des Mammi‘eres fossiles de llonzon,” Annales des 8ciencos Oeologitpies, vol. xii. (1882). II “ 8tructuro ami lielationshij)s of ylncodus,” Journ. Acad. Nat. 8ci. Phihulelpliia, [2] vol. ix. (1884-95) p. 461. ANCODON GOKlilNGEr. 179 Ancodon gorringei, Andrews & Beadnell. [Plate XYIII. figs. 1, 2, 3; text-figs. 60, 61.] 1902. Ancodus gorringei, Andrews & Beadnell, A Preliininaiy Note on some new Mammals from the Ujiper Eocene of Egypt (Survey Dept., Cairo), p. 7. Type Specimen. — A mandible wanting the ascending ramus of the left side (PI. XVIIl. figs. 1, 1a); Geological Museum, Cairo. This is the larger of the two species found in these beds. The extreme length of the jaw exceeded 34 cm. ; the length of the symphysis 9 cm. ; length of the molar series 7'2 cm. Remains are fairly common, and, in addition to the lower jaw and dentition, the iipper molars and premolars, some vertebrae, limb-bones, and tarsals are known. Form. ^ Log. — Fluvio-marine beds (Upper Eocene) ; north of Birket-el-Qurun. C. 8629. Mandible, wanting ascending ramus on left side. On the left side only the molars are preserved, but on the right there are also i. 1, i. 3, pm. 2, pm. 3, and jom. 4; 2 and c. are represented by their alveoli only, pm. 1 by its broken base. Type specimen described by Andrews and Beadnell, loc. cit. Figured on PI. XVIII. figs. 1, 1a. This mandible is very long, owing mainly to the great elongation of the spout-like symphysis (sgm.), the upper surface of which is gently concave from side to side, while the ventral surface is convex in the same direction wdth a slight median ridge, which forms a small projection posteriorly. This form of the ventral surface of the symphysis differs considerably from that seen in A. velaunus, in which not only is this region somewhat shorter, but the posterior portion of the ventral surface is flattened in front and concave behind. The horizontal ramus is slender ; its ventral border, which is thickened and rounded from side to side, is neaidy straight from before backwards beneath the premolars and slightly convex beneath the molars. Behind this the ventral edge thins and is slightly concave, and then passes down into the rounded angle of the jaw, which does not form a vertical process projecting considerably below tin; rest of the mandible as in some species, e. g. A. hovinus and A. aymardi. The outer face of the horizontal ramus beneath the premolars is concave from above downwards, beneath the molars it is flat or slightly convex ; its greatest de[)th is beneath the last molar. Behind the last molar the rami diverge rapidly. The anterior border of the ascending ramus is coTivex and slopes back to the summit of the coronoid process {cor.), the posterior border of which is slightly concave ; it rises considerably above the level of the condyle (co7ul.), which is transversely elongated and is convex from before backwards and nearly flat from side to side. The posterior region of this mandible is imperfectly preserved. The incisors are procumbent: i. 1 is the smallest; k 2, here w^anting, was probably the largest ; i. 3 has a small hastate crowm, the lower face of which is strongly convex, the upper flat or gently concave ; the root is relatively very large. The canine (rejtresented by the alveolus only) is separated in trout from i. 3 by a short diastema (•8 cm.) and behind from prn. 1 by a longer interval (2‘2 cm.). Pm. 1 is re})resented 2 A 2 180 TEliTJAEY VEETEBEATA OF THE FATtlM. only by a singlo-rootcd stnni]), and between it and pm. 2 is a s])ace of 2'5 cm. Pm, 2 is a two-rooted tooth with a compressed conical crown, tlie anterior and posterior borders of whicli form sharp edges. A ridge runs down from the summit on the ])Os((‘ro-internal surface, dividing tlie inner face into a larger anterior fossa and a smaller posterior rugose fossa, which looks inwards and backwards. The cingulum is developed on the inner side of the tooth, particularly towards the posterior end, and it is also present for a short distance on the postero-external side. The third premolar is, on the whole, similar to yrut. 2, from which it is separated by a short interval. The cingulum, however, is l)etter developed, and forms a sort of small talon })osteriorly. The postero-internal ridge is also more strongly developed. The fourth ])remolar is larger and is much wider posteriorly, where the cingulum forms a well-marked prominence ; the postero-internal ridge is still more strongly developed, its lower end almost forming a tubercle, though it cannot be said that, even in this tooth, there is any distinct inner cusp. The molars consist of two pairs of cusps, the outer being crescentoid, the inner ])yramidal ; both are much lower than in the typical Oligocene s])ecies of the genus, and approximate closely to the type seen in Prachpodas, so that if it were not for the greatly elongated symphysis this animal might perhaps have been referred to that genus. In wear, the anterior limb of the postero-external crescent is seen to be divided into two ridges, one running forwards and inwards across the main transverse valley to the base of the antero-internal cusp, the other running inwards and joining a ridge running forwards from the postero-internal cusp, thus forming the anterior boundary of a fossa lying between the outer and inner posterior cusps. In Prachpodus and the later forms of Ancodon the same fossa is present, but its anterior border is formed by the main anterior arm of the postero-external crescent. The talon of m. 3 consists of a large crescent forming its outer side and a prominent ridge forming its inner edge, the two enclosing a w^ell-delined fossa. The talon, as a whole, is broader and more massive than in the later forms of Ancodon, and is much like that found in PmcJipodus. The dimensions (in centimetres) of this, the type specimen, are : — Approximate lengtli of mandible „ „ symphysis Depth of ramus behind 3 Height at coronoid The dimensions ( in centimetres) of the teeth are : — 2 pm. 3 2011. 4 no 1 ')ii. 3 Lengtli of molar series 7'2. Length of |)remolar pm. 1) 8'(). 34 9 4-5 11 app Length. Width. 1-5 •'.» 1-8 M 1-8 1-2 1-7 1-2 2 1-6 3-3 1-8 series (including The diastema between the canine and pm. 1 is 2‘2, that between pm. 1 is 2'r). and pm. 2 M. 8881. ITaster cast of the above specimen. Made in the British Museum. ANCODON GORRINGEl. 181 M. 8424. Palatal roo-ioii of skull with toetli. On tlio right si are preserved, on the loft wo d is wanting. Right side lignred PI. XVII I. tig. d. In the figure pm.?> is drawn in outline from another specimen (M. 842.5). The fourth premolar consists of an outer crescentic cusp and a large inner rounded tubercle ; the cingulum is well developed on the inner side. This tooth resembles the fourth j)remolar of the other species of Ancodoyi and differs from that of Braclnjodus in the absence of a postcro-internal cusp. The molars increase regidarly in size from before backwards. They are quadrate in outline, and as in the other members of the family are com])osed of five main cusj)S, three anterior and two posterior. These cusi)s are lower and much less distinctly selenodont than in the other species of Ancodon (?xcept A. porcinus, Gerv., a species which Lydekker* has shown to be intermediate in molar structure between the typical species of Ancodon and Antliracotkerium. The outer wall is strongly folded into a W-shaped ectoloph, the parastyle and inesostyle being very prominent in all the molars, while in m. d there is a large metastyle also. The cingulum is strongly developed and continuous round the anterior and inner sides of the teeth. This also seems to be the case in A. porcinus and in Bracliyodus, while in the more hypsodont species of Ancodon the cingulum is almost wanting on the inner side of the teeth, and in Anthracothet'ium it is absent on the inner side of the inner main cusps. The dimensions (in centimetres) of the teeth are : — Length. Breadth. pm. 4 1'2 1'6 m. 1 1-G 1-8 m.2 2-2 2-2 m. 3 2-5 2-5 Length of molar series 5'8. M. 8425. Right maxilla with pm. 3-4 and m. 1-3. The first and second molars are incomplete on the outer side. Pm. 3 consists of a long trenchant outer cusp rising to a sharp point ; internally the cingulum is well developed and forms a sort of shelf-like 2:)rojection on the postero-internal face of the tooth, which is therefore triangular in outline. This tooth is borne on three roots, one beneath the anterior angle, the others arranged transversely beneath the wider posterior portion. This tooth is shown in outline on PI. XVIII. fig. 3. (pwn 3). The dimensions (in centimetres) of the teeth are : — Length. Breadth. pm. 3 1’6 1'4 p??i.4 1'4 1‘7 m. 1 m.2 2-2 app. m. 3 2-6 Length of molar series approximately 6'1 cm. M. 8423. Portion of palatal region of skull with pm. 3-4, m. 1-3 on the right side, and m. 3 on left. The length of the molar series is 6 cm. * “ Note on the Anthracotheriidae of the Isle of Wight,” Qeol. Mag. [3] vol. i. (1884) pp. 547-8. 182 TEJiTIARY VERTEBEATA OF THE EAYtM. ip])er molars and ]»rem olars. In this specimen pm. 3 has a small postero-internal apparently belonging to the cingulum. The dimensions (in centimetresj of the are : — Length. Breadth. pm. 3 LG ^//«.4 1-5 1-7 1 1-7 1-7 TO. 2 2-1 2-3 ?)i. .3 2-7 Length of molar series 6-2 cm. C. 8630. Portion of left maxilla with mncli broken m. 2 and m. 3 ; similar to C. 8814. C. 8983. Nearly complete right ramus of mandible with p/a. 2-4 and m. 1-3. Length of molar series 7'2 cm. M. 8505 a. Portion of right ramus of mandible wilh p/n. 4 and m. 1-3. Length of molar series 7 cm. M. 8505b. Portion of left ramus of mandible of a smaller individual with p?n. 4 and m. 2-3. The enamel shows the peculiar sculpturing consisting of fine irregular ridges. Length of molar series G‘4 cm. M. 8428. Portion of right ramus of mandil/le of a young individual with unworn m. 2-3. Figured on Ihate XVIII. fig. 2. Length of /a. 2, 1‘8 cm. ; length of ■/?/. 3, 3'0 cm. C. 9295. Portion of right ramus of mandible with the molars. Length of molar series 7'.7 cm. (app.). C. 8623. Portion of right ramus of mandible with p/a. 2-4 and m. 1-3. Length of molar scrie.s G’9 cm. C. 8975. Portion of mandible of a much older individual. Much more massive than C. 8983. Length of molar series 7‘G cm. C. 8825. Fragment of right ramus of young mandible with m. 2 and rn. 3 ; the latter is just being cut ; its length is 3'2 cm. M. 8427. Portion of left ramus of mandible with pm. 3-4 and m. 1-2. M. 8506a. Posterior j/ortion of right ramus of mandible. Length of m.3, 3'4 cm. M. 8506b. Fragment of left ramus of mandible. Length of in. 3, 3‘1 cm. C. 8827. Left ramus of mandible with m. 2 and m. 3. Length of m. 3, 3*2 cm. C. 8615. Portion of left ramus of young individual with ni.2 and ///. 3 ; the talon of »/. 3 is smalh'r than usual. Length of in. 3, 2'8 cm. The following s])ecime]is are ])i-ovisionally rcLwred to this species : — C. 9232. Posterior cervical vertebra, wanting j/osb/rior epiphysis. The arch is very broad and massive, th<^ zygapo])hyses being excej/tionally largo ; there is no neural spine ; a vvirtebrarterial canal is present, but the transverse j/rocess is broken away. Width ol centrum 8 cm. (a])]).) ; height of ditto G'5 cm. ; height to top of arch lO’f) cm. ANCODON GOKllINGEr. 183 C. 9233. Anterior dorsal vertebra, wantiiif); tlie e|)i[)liysis. In this the centrum is slightly opistlio- coelous ; the neural s])ino is large, backwardly directed, and narrowing to a point ; strong transverse processes directed upwards and outwards ; posterior zygaj)opliyses flat and looking nearly directly downwards. Large concave surfaces for the heads of ribs at upper angles of ])osterior face of centrum. Width of centrum 7’5 cm. (app.) ; height of ditto G'5 cm. ; height to top of neural spine 14+ cm. ; width between ends of transverse processes 14’G cm. M. 8867. Posterior dorsal vertebra of a smaller animal, (lentrum wanting epi[)hyses ; deeper than wide and v\ith a strong hypapophysial ridge : shallow facet for rib-head about the middle of the pedicle of the neural arch ; neural s[)ine sloping strongly backwards. Width of centrum 5 cm.; height of ditto 4'5 cm.; height to top of neural spine 13+ cm. Presented by the Egyptian Government, 1904. C. 7884. Nearly complete lumbar vertebra, wanting posterior epiphysis. The centrum is a little higher than wide, at least posteriorly ; it has a strong hypapophysial ridge, and its neural surface is strongly concave from side to side. The neural arch is high and the neural spine is a broad thin plate of bone abruptly truncated at its upper end and sloping very little backwards. The posterior zygapophyses are large and overhang the hinder border of the centrum ; the anterior zyga[)ophysial surfaces are slightly concave from side to side ; the transverse process is broken away. M. 8867a. Imperfect lumbar vertebra, similar to last, but of a larger individual. Presented by the Egyptian Government, 1904. C. 8637. Glenoid end of right scapula. The glenoid cavity is nearly circular in outline, and separated from it by a notch is the strongly recurved coracoid process, which does not quite reach the level of its margin. The glenoid border in the region of the neck is flattened and bears a small but well-deflned pit. This bone differs from that of Eiplopus in the relatively smaller size of the much more recurved coracoid process, in the absence of a deep fossa on the glenoid border of the neck, and in the more nearly circular outline of the glenoid cavity itself. Fragments of scapuk® from Hamstead Cliff, referred to Ancodon, differ in having no distinct coracoid notch, a larger coracoid process, and a more oval glenoid cavity. Antero-posterior diameter of glenoid cavity 4'8 cm. Total width with coracoid process 6'5 „ Width of neck 4’1 „ M. 8510. Glenoid end of right scapula, similar to last specimen. Presented by W. E. de Winton, Esq., 1903. C. 8855. Distal end of left humerus. This resembles very nearly the distal ends of some humeri from Hamstead, presumably belonging to Ancodon. The inner portion of the trochlea is larger than in Eiplopus, and is not produced down into a thin flauge-like edge. The intertrochlear ridge is much narrow'er and sharper than in that genus. There is a small supratrochlear perforation. The inner condyle forms a large blunt prominence on its inner side and is produced backwards into a posterior ])rojection, the distal border of w'hich is at right angles to the posterior border. The shaft was comparatively slender. The dimensions (in centimetres) of this specimen are : — Width of shaft 3; greatest width of distal end 5'2 ; width of distal articulation 3‘8. 184 Tl']irL'IAliY VEETEHIiATA OF THE FATtlM. M. 8509. Distal ends of tlireo Ininieri of similar form to C. 8G55. H. 8430. Distal oiuls of two right humeri. C. 8652. Distal end of right humerus of a similar form, l)ut considerably larger size, the width of its distal articular surface heiug 4*7 cm. against 3'8 cm. in C. 8G;'35. M. 8862. Distal ])art of right humerus. In this specimen there is a su])ratrochlear perforation. Tlu^ dimensions (in centimetres) are: — Width of shaft 3; width of distal end G; width of distal articulation 4’, 5. Presented Inj the Etian Government, l'JU4. C. 8124. Left radius. This hone is comparatively long and slender, hut it widens out considerably towards the distal end. The anterior face of the shaft is convex, the posterior (idnar) surface flattened. The proximal articular surface consists of a hu'ger outer portion, deeply grooved towards its inner side for the intertrochlear ridge of the humerus, and a smaller inner portion only very slightly concave from before backwards and looking upwards and inwards : this, with the large inner portion of the sigmoid surface of the ulna, articulates with the inner portion of the distal articulation of the humerus. About the middle of the posterior face there is a ])romineut facet for articulation with the ulna, but in addition to this the whole posterior surface seems to have been ridged and roughened, showing that the union between the two bones was a very close one. The distal articulation is unknown. The dimensions (in centimetres) of this specimen are : — "Width of j)roxinial articular surface 4-7 „ uiiddle of shaft 2-4 „ distal end 5-3 Length (without distal epiphysis) 31‘4 M. 9124. Incomjdete left radius similar to last. M. 8863. Upper portion of a left ulna. The olecranon process is large and rises high above the articulation, but ]3rojects veiy little backwards. The inner boialer of its upper end is produced upwards into a flange which forms the inner side of a large groove (? for a tendon). The sigmoid notch is shallow and except towards the upper end the surface for the humerus is on the inner side only. There is a small distal surface for the outer side of the humeral articulation, and immediately beneath it is the projecting facet by which the bone interlocks with the upper end of the radius, which must also have been closely united with the rugose anterior face of the shaft. This becomes considerably nari'owed towards its middle and is strongly compressed from before backwards, though less so than iii JJij)lopiis ; towards the distal end the radial surface forms a sort of shelf on the inner side of the shaft and is bordered externally by a strong ridge. The distal extremity of the bone is unknown. The dimensions (in centimetres) of this specimen are : — Greatest antero-posterior width of olecranon process .... A'S Height of olecranon above articulation (!'7 Length of sigmoid notch 4'4 W'idtli ot surface for upper end of radius 3'() I’resenled by the Egyptian Government, 1904. 1’ resented by the Egyptian Government, 1904. M. 8863a. Upper end of a similar right ulna. ANCODON GOEEINGEI. 185 C. 8836. Left nlna, wanting tlio distal end. This specimen shows that this hone is long and slender. The dimensions (in centimetres) are : — Length of sigmoid notch 4’7 Height of olecranon process above articulation 5*5 Length of bone so far as preserved 38 C. 8805. Left os inuominatum (text-fig. GO). The long axis of the ilium (il.) is nearly on the same straight line as that of the ischium (isG.). For a short distance in front of the Text-fig. 60. Left os innominatum of Ancodon gorringei : A, from side ; B, from below. acet., acetabulum ; foramen formed by closure of the cotylar notch (the passage into the acetabulum is marked by a line from/.); iZ., ilium ; isc., ischium ; isc.<., ischial tuberosity; Z.i., pit for ligamentum teres ; m., pit for attachment of a muscle, probably the rectus femoris ; obt.f., obturator foramen ; pt., pectineal tubercle ; yjw., pubis ; sac.s., surface for sacrum ; sym., sympbysial surface of pubis, i nat. size. acetabulum the upper and lower borders of the laterally compressed neck of the ilium are nearly parallel, then the bone expands greatly into a roughly triangular region, the inner (sacral) face of which bears a large and clearly defined surface for the sacrum (sac. 5.) ; this surface is bounded ventrally and separated from the lower border of the bone by a rounded ridge. The upper edge of the ischium is thin and sharp, and there is a slightly developed superior ischiadic spine ; posteriorly the bone expands and bears a large 2 B ISO TEllTIAKT VEIiTEBRATA OF THE FATtJM. fl:iltciio(l iscliial iubcirosity {isc.t.). The outer surface of the ischium is in almost the same plane as the <>luteal surface of the ilium. The })ubis (pu.) is a stout bar of bone compr(!sse(l from above downwards. On its anterior border beneath the acetabulum is a well-marked pectineal tuberosity towards its inner end it widens out and terminates in a flat oval surface by which it unites in symphysis (sym.) with its fellow. Behind this surface there runs back to the ischium a thin bar of bone, closing the obturator foramen. This bar has a thin shar]) edg'e, and neither it nor the ischium seems to have united with the corresponding portion of the opposite os itmominatum. The obturator foramen [obt.f.) is an elongated oval. The acetabular ' cup (acet.) is nearly circular in outline ; it is deep, its edges being prominent and thickened, ])articularly in front. Its border is complete, there being no cotylar notch, which is only represented by a j)assage (/‘.) running through the posterior wall of the acetabulum from just above the anterior end of the obturator foramen and opening into the posterior end of the pit for the ligamerdum teres Q.f.), which is a deep elongated depression at the bottom of the acetabulum. This arrangement is also found in a very similar pelvis of Braclujodus afrlcanvs from Moghara and in Hippopotamus : this last gxmus, in fact, seems to b(' intimately related with these African Anthracotheres, and annectant forms similar to Meriicoj'iotaiiuis will jirobably be discovered in the Miocene beds between JMoghara and the Wadi Natrun, in the Lower Pliocene deposits of which remains of a primitive Hippopotamus have already been found. The dimensions (in centimetres) of this specimen are : — Total length of os inuoiuinatum 37’2 „ ilium from centre of acetabulum 20‘4 „ ischium from centre of acetabulum .... 17'0 Width of peduncle of ilium 6 „ crista ilii IGA Diameter of acetabulum 5-2 Length of obtui’ator foramen 9'4 Width of pubic bar on inner side of obturator foramen ... 1 •.'i Length of symphysial surface of pubis 5'5 Depth of symphysial surface of jiubis 3 M. 9242. Plaster cast of the al»ove specimen. Made in the British Museum. C. 9224. Portion of left os innominatum, wanting part of front of ilium and the pubis. M. 8866. Portion of left os innominatum. Presented hij the Bgpptian Government, 1901. M. 8864a. Complete left tibia. The most notable character of this bone is the slenderness of its distal |)ortion compared with the heaviness of its upper end. The outer facet for the femur is concave from side to side and strongly convex from before backwards ; its inner edge forms a rounded ridge separated by a groove from the raised outer edge ol the inner facet, the two together forming a bifid intercondylar prondnence. The inner facet is concave from side to .side and nearly flat from bcd'ore backwards. In front of the articular surface the u])per end of the large cnemial crest forms a broad tlattened surface. The upper ])ortion of the shaft is trihedi'al ; its antero-external side is deeply concave, the jiosterior slightly so; this lath'r face is overhung by the jiosterior border of tlu' proximal articulation. Tin* cnemial crest disa|)pears about hallway down the shall, ANCODON GOREINGEI. 187 which beneath this point becomes much more slender, expanding again a little towards the distal articulation. The distal articulation is quadrate in outline, and its outer border is occupied by a large I'acet for the fibula, looking outwards and downwards. The groove for the outer half of the astragalar articulation is both broader and shallower than the inner, which is very narrow and is deepened anteriorly by the presence of a strong internal malleolar ])rocess. The dimensions (in centimetres) of this S})ecimen are : — Extreme length 40'5 Width of proximal end 10 „ distal end 6-2 Antero-posterior length of distal articulation 4-2 Width of shaft at narrowest 3‘8 Presented hy the Egyptian Government, 1904. C. 8899. A similar right tibia, of which the dimensions (in centimetres) are : — Extreme length 39 AVidth of proximal end 10 „ distal end 5'4 ,, shaft at narrowest 3’7 C. 9312. Eight tibia of rather more slender form, probably of a different species. A very prominent thin internal malleolus. The dimensions (in centimeti'es) are : — Extreme length 41 AVidth of proximal end 9 „ distal end 4'6 „ shaft at narrowest 3‘4 M. 8864b. Right tibia, similar to M. 8864 a, but wanting the proximal epiphysis. Presented hy the Egyptian Government, 1904. M. 8507. Right astragalus (text-fig. 61). In this bone the relative heights of the outer {ox.) and inner condyles {ix.) of the proximal trochlea are about as in astragali of Ancodon (dlyopotamns) from the Isle of AVight, but the outer condyle is rather more massive. In the distal trochlea the cuboid surface {cvb.) is I’elatively rather wider, and the keel between it and the navicular surface (nav.) less prominent than in the European species. The sustentacular articulation {sus., sus.') seems to be closely similar to that described by Scott * in the American species — that is to say, it is divided into an outer facet (sus.), nearly flat from side to side, but convex from before backwards and looking towards the plantar surface, and an inner (sus.'), in this case much narrower, facet, which does not extend quite so high up proximally, but further distally, the distal portion being an almost distinct rounded surface ; this internal portion of the sustentacular articulation looks towards the outer and plantar surface. Of the outer calcaneal facets the proximal one (ect.) is divided by a deep depression into proximal and distal portions, of which the latter is borne on a strong prominence and looks mainly towards the * u The Structure and Relationships of Ancodus,” Journ. Acad. Nat. Sci. Philad. [2] vol. ix. pp. 482-83. 188 TERTIAET VERTECEATA OE THE EAYtM. plantar surface. Beneath it the outer surface of the hone is deeply excavated. The distal (ialcaneal facet [calc.') is large and fiat, looking outwards and a little downwards. The ditnensions (in centimetres) of the specimen above described are : — Greatest length 7'G AVidth of proximal articulation 3'5 „ distal articulation 3'8app. ,, sustentacular articulation 2 7 C. 8388, C. 9004, C. 9043-4, C. 9276. Right astragali. C. 8431. Two right astragali, rather smaller than M. 8507. C. 8412. Left astragalus. M. 8431a, M. 8507. Left astragali. C. 8810. Left astragalus, from highest beds. Text-fig. 61. Eight astragalus of Ancodon fjorrinrjei-. A, from behind ; B, from outer side. distal calcaueal facet ; c\d)., facet for cuboid ; ec<., ectal facet (divided into two) ; i.c., proximal inner condyle ; 7i«y., facet for navicular ; o.c., proximal outer condyle ; sus., sks.', outer and inner portions of sustentacular facet. nat. size. M. 8432. Right calcaueum, wanting the tuhcn- calcis. The sustentaculum is large ; it hears two facets, a larger outer one, concave from before backwards, and looking uj)wards, and a smaller inner one looking upwards and inwards. The ectal facet is also divided into a larger posterior jiortion looking inwards, and a smaller anterior portion looking upwards and se[)arated from the large fibular facet by^ a notch. On the outer side ol the bone, beneath the fibular facet, there is a deeji fo-ssa, hounded below by a broad ridiro, wliicli runs forwards to the lower end of the bone, and at the same time forms O / ' the ujiper limit of a broad longitudinal groove which runs along the distal half of tin* outer face. The anterior astragalar facet is flat and looks nearly inwards ; the cuboid facet obliquely truncates the distal end of the bone. On the whole, this hono much ANCODON GOEEINOEI.— ANCODON PAEVUS. 189 reseml)les tho calcaneiim of Diplopus figured and described by Kowalevsky*. The dimensions (in centimetres) of tins specimen are : — Greatest width from above downwards 5’7 „ „ „ side to side 4-5 Width of sustentacular surface 3'2 M. 8516 b. Portion of right calcaneum similar to last. Presented hy \V. E. de Winton, Esq., 1903. M. 9224. Left cuboid. C. 7993. Right calcaneum. Length 14’5 cm. C. 8387. Portion of left calcaneum. M. 8516 c. Proximal end of (?) the third left metatarsal. This bone seems to have interlocked with the second metatarsal, as in Ancodon, as figured by Kowalevsky. The shaft of the bone is much compressed from before backwards. The lateral (2nd) digit must have been of considerable size. Presented by W. E. de Winton, Esq., 1903. C. 8894. A metapodial bone (? third metacarpal), 11’5 cm. long. C. 7990. Portion of metapodial. M. 9127. Distal ends of two metapodials. Ancodon parvus, sp. nov. [Text-fig. 62.] Type Specimen. — A portion of the right ramus of a mandible with m. 1 and m. 2 in situ, together with the empty alveolus of 7n. 3 (text-fig. 62) ; Geological Museum, Cairo. This species differs from A. gorringei in its considerably smaller size. The molars also differ in the following points: — (1) The cusps seem to be relatively higher; (2) the cingulum is much more strongly developed on the posterior end of the tooth ; (3) the teeth are longer in proportion to their width; (4) the enamel is nearly smooth. Possibly when more is known of this species it may be necessary to refer it to a distinct genus. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. C. 8821. Part of tho right ramus of the mandible with m. 1 and m. 2 in perfect preservation. Type specimen (text-fig. G2). The depth of the jaw beneath m. 2 is 1‘8 cm. The dimensions of the molars (in centimetres) are : — Length. Width. }?i. 1 1’2 *6 m.2 1-5 -9 The length of m. 1 and m. 2 together is 2' 7 cm. ; in A. gorringei this measurement is 3'8 cm. * “ On the Osteology of the Hyopotamidce,” Phil. Trans, vol. 163 (1873) p. 53, pi. xxxv. fig. 4. 190 TERTIARY VERTEBRATA OF THE FAYtJM. To this spocios a minil)er of more or less imperfect bones of an Artiodactyl smaller than A. (jorriiKjei may he jtrovisionally referred. These are enumerated below. M. 8429. Right scapula with large portion of the blade preserved. The articular end is like that already described. Above the neck the blade expands rapidly; the postscapular fossa is concave from side to side, and widens rajiidly towards the suprascapular border ; the ])rescapular fossa also widened rapidly, but the upper anterior portion of the blade being broken away, its exact form, as well as that of the coracoid border, cannot be made out. On the whole, this sca})ula seems to have resembled that of Diplopus figured by Kowalevsky (Phil. Trans, vol. 1G3, 1873, pi. xxxv. tig. 1) rather than that of Ancodon hrachyrliynclMS figured by Scott (Journ. Acad. Xat. Sci. Philad. [2] vol. ix. 189.5, p. 474). The dimensions (in centimetres) of this specimen are: — Width of glenoid cavity 3’8 ; width of neck 4'2 ; width of blade at widest part preserved 12. Text-fig. G2. C. 7832. Glenoid end of left scapula, probably of a smaller species. Width of glenoid cavity 3‘5 cm. (app.) ; width of neck of scapula 2*7 cm. C. 8640. Glenoid half of a left scapula, showing that the spine was high and terminated in a free acromion process. Width of glenoid surface 3'8 cm. ; height of s{)ine (app.) 3 cm. C. 9289. Right humerus, wanting the proximal end. The deltoid crest is very slightly developed : the lower part of the shaft is nearly circular in section. There is a supratrochlear perforation ; the trochlear ridge is more strongly developed than in JHplopus. The dimensions fin centimetres) of this specimen are : — Lengtli so far as preserved 19 Widtli of shaft at narrowest point 2-2 „ distal end 5 „ distal articulation 3'3 M.8516. Proximal ends of two radii. Prcsenled by IP. K. de Winton, Esq., 1903. ANCODON PAllVUS— RlIAGATJIEllIUM. 191 M. 8508. Upper part of a loft ulna similar to that of A. (jorrhujei. Tlio dimensions (in centimetres) are : — Antero-posterior width of the olecranon process 4 app. Length of sigmoid notcli 3'5 Width of surface for radius 2 Presented by W. K. de Winton, Esq., 1903. M. 8508 a. Upper end of similar right ulna. Presented by W. E. de Winton, Esq., 1903. M. 8508b. LTpper half of an abraded right ulna of rather smaller size. Presented by W. E. de Winton, Esq., 1903. C. 8641. Proximal end of right ulna. M. 8516 a. Distal end of right tibia. Width of articulation 3'8 cm. Presented by W. E. de Winton, Esq., 1903. M. 8431. Right astragalus. Width of proximal articulation 2’6 cm. ; greatest length 6*2 cm. M. 8507. Left astragalus. Width of proximal articulation 2'7 cm. ; greatest length G‘2 cm. Presented by W. E. de Winton, Esq., 1903. C. 8636. Somewhat smaller left astragalus. Greatest length about 5‘4 cm. Ancodon sp. Two associated right upper molars (m. 2, m. 3) of about the same size as those of A. gorrinyei, but differing from them in possessing higher, sharper, and more selenodont cusps, were collected by Mr. Beadnell. This specimen indicates the probable existence of another species of Anthracotheroid which approaches more nearly to the later typical species of Ancodon (e. g., A. velatinus) than does A. gorringei. At the same time the evidence does not seem sufficient to warrant the establishment of a new species. Form. & Log. — Fluvio-marine beds (Upper Eocene): north of Birket-el-Qurun. C. 10500. Two associated right upper molars (to. 2, m. 3). The outer side of m. 2 is partly broken away. The dimensions (in centimetres) of these teeth are : — Length. Width. TO. 2 1'6 l‘6app. TO. 3 1-9 2 M. 9242. Plaster cast of the above specimen. Made in the British Museum. Genus RHAGATHERIUM, Pictet. [Memoire sur les Animaux Vertebres trouves dans le Terrain Siderolithique du Canton de Vaud, p. 43 (1855).] This genus was founded by Pictet {loc. cit.) for the reception of a small species of Anthracotheroid in which the incisors are small, while the canines have cutting-edges 192 TERTIAEY VEETEBEATA OF THE FAYtM. and are separated both from the incisors "and premolars by long diastemata. In the ni)pcrja\v there are four premolars, 1 being separated from 2 by a diastema. 'I'he molars have very brachyodont crowns, the cusps being only slightly selenodont but strongly convex on their outer face. The type species is R. valdense. Later, Kowalevsky * described and figured another species, B. fronstettense, in which the upper molars are still more bunodont, the cusps being shorter and thicker; the middle fold of the outer wall [mesostyle) is also more strongly developed, as, judging from the figures, is the cingulum generally. A single tooth from the Upper Eocene of the Fayum resembles those figured by Kowalevsky so closely in its structure that it is here referred to the same genus, though, on account of its much greater size, to a distinct species. Rliagatlierium aegyptiacum, sp. nov. [Plate XVIII. fig. 5.] Type Specimen. — Left upper molar, probably the third (PL XVIII. fig. 5); British Museum. The tooth upon which this species is founded is clearly that of a primitive Anthracotheroid, in which the selenodont condition of the molars of the later forms is still only indicated, and the cusps are low and strongly convex on the outer as well as on the inner face. There are three main cusps in front and two behind, as usual in the family ; the intermediate anterior cusp is the smallest. The cingulum is well developed round the whole crowm, with the exception of the outer face of the })ostero-cxternal cusp. The fold on the outer face between the main cusps forms a w’cll-developed mesostyle. In wear, the inner cusps would tend to give a V-shaped pattern, but this would not be the case with the outer ones. The tooth differs from those of B. valdeme, Pictet, and B. fronstettense, Kowalevsky, by its much larger size, and from the former by its still more bunodont crown. Possibly, wdien the dentition is fully known, it may be necessary to establish a new genus for this species. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-et-Qurun. M. 8449. Left upper molar, probably the third ; the low cusps are Just coming into wear. Type specimen, figured PI. XVIII. fig. .5. The length of this tootli is 1'8 cm.; its greatest width 2 cm. In 11. va/den.'^e the corresponding measurements are ‘75 cm. and ’8 cm.; in IL fronstetlense they are 1 cm. and 1 cm. *■ “ Monographie der Gattuug Anthmcolherium, Cuv.,'’ rala.'outograpliica, vob xxii. (1876) p. 228, pi. viii. figs. 57, 58. GENIOIITrS MIEUS. 103 Family SUID.E. The peculiar genus Geniohjus may be referred provisionally to this family, of which it may be taken as representing a distinct subfamily, the Geniohyince. Further knowledge of this remarkable form may lead to the establishment of a new family for its reception, but at present the course here adopted seems best. Genus GENIOHYUS, Andrews. [Geol. Mag. [.5] vol. i. (1904) p. IGO.] Known only from the mandible and lower teeth. The dental formula for the mandible seems to be i. 3, c. 1, ym. 4, m. 3, but possibly the canine may be wanting, as will be explained below. The anterior incisors are enlarged and procumbent ; the premolars are all simpler than the molars, which are bunodont. The mandible bears on its lower border, immediately behind and beneath the symphysis, a pair of large backwardly-directed processes. Three species of this genus are at present known. Genioliyus mirus, Andrews. [Plate XIX. figs. 1, 1a.] 1904. Geniohyus minis, C. W. Andrews, Geol. Mag. [5] vol. i. pp. 160-161, pi. vi. fig. 4. Type Specimen. — Symphysis and part of the right ramus of a mandible with the premolars and molars well preserved (PI. XIX. figs. 1, 1a); Geological Museum, Cairo. This is the smallest of the three species, and at the same time the premolars are the simplest. Length of the premolar series is 5 cm. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. C. 8634. Symphysis and part of right ramus of mandible. Type specimen described and figured loc. cit. supra ; also PI. XIX. figs. 1, 1 A. The spout-like symphysial region is narrow both from side to side and from above downwards, and behind it, just where the rami begin to diverge, the ventral border of the jaw is produced downwards and backwards on either side into a long backwardly directed process (pr.), which is oval in section and probably ended in a point, hut the tip is broken away. The hinder border of the base of this process is connected with the lower edge of the horizontal ramus by a thin plate of bone. The ramus is incomplete ventrally, but was evidently narrow from above downwards. The function of the peculiar paired ventral process is uncertain. In the Dinocerata a somewhat similarly situated prominence on the mandible helped to protect ]04 TEliTJAllY YEETEBliATA OF THE FATCM. Ilio ])oini of tlie T]])])or canine tusk, while in IJlotheiium, a more nearly related form, tli('re ar(> sometimes two ])airs of such processes, but they are directed downwards and mor(' or less club-shaped: iu the latter genus also their function is uidviiown. On the side of the jaw' there are several foramina. The most anterior of these is immediately behind the alveolus of i. 1, the next tw'o are beneath i.3 and c., while the last is behind the posterior border of the symphysis at the level of 2. The first ineisors (i. 1) are broken ofl' short, but it can be seen that they were greatly enlarged and directed forwards. They were laterally compressed so as to give an elongated oval outline in section ; the outer side, at least, was enamel-covered. The second incisor (?'. 2) was a small rounded tooth, represented in this specimen by its alveolus only. Behind this, at an interval of about cm., is a small rounded root of a tooth and immediately behind this a second rather larger. The nature of these is doubtful : they look as if they might be roots of one tooth, but since from their position this is not probable, they are here regarded as the roots of the third incisor (h 3) and the canine (r.). The distance betw'cen the canine and first premolar is about 1 cm. This enlargement of the anterior incisors and the very small size of the canine distinguish Geniohi/us from the other members of the family, and at least justify its separation in a distinct subfamily. The anterior premolar 1) is a compressed tooth consisting of small anterior and posterior tubercles and a high main cusp. In the next (/7m. 2) there is a small cingular ridge in front of the tooth and the main cusp is much larger, showing a tendency towards division into an outer and an inner element. In wear it gives a triangular surface, from the outer angle of which a ridge runs down the outer face of the tooth, w'hile from its front angle there is a small ridge connecting it with the anterior tubercle, and similarly posteriorly a small ridge unites it with the posterior tubercle. The next tooth (pin. 3) is similar, except that the [)osterior lobe is larger and shows a tendency to give a V-shaped surface in wear. In the last premolar {jiin. 4) the replacement of the main cusp by two elements is complete, the inner being small and rounded, the outer larger and V-shaped in wear. From the anterior arm of the V a small ridge runs to the small anterior tubercle, while from the posterior a low ridge runs back uniting it with the anterior limb of the V-shaped posterior lobe. On the inner side of this last there is a trace of a small inner tubercle corresponding to the postero-internal cusp of the molars. The characters of the molars are those of a ])rimitive mend)er of the Suidos, in which the outer cus})S are distinctly selenodont. Each molar consists of two pairs of cusps, the outer V-shajied, the inner more rounded or ])yramidal. In the tirst molar (m. 1) the out(‘r cusp is considerably w'orn ; it consists of the main tubercle forming the apex of the V, of which the arms form slight ridges terminating in small accessory tubercles, of which the anterior is situated on the anterior border of tbe tooth, while the posterior is connected by a slight ridge with the postero-internal angle of the inner cusp. The jiostero-external cusp shows the selenodont character still more clearly: its small anterior accessory tubercle partially fills the main transverse valley ; the posterior accessory tubercle is on the hinder border of the tootlu. The internal cusps are trihedral, and in wear they also show some tendenc:y to form a V-shaped surface, the opening of the V of the antero-internal cusp looking outwards and backwards, that of the postero- internal cusp outwards and forwards. There is a slightly developed cingulum on the outer siile of the tooth, most marked opposite the opening of the transverse valley and GENIOIITUS MIRUS— GENIOIITUS FAJUMENSIS. 195 near tlie anterior end o£ the tooth. Tho second molar (m. 2) is similar to the first, except that on tlie hinder border there is an additional minute tubercle lying internal to tho posterior accessory tubercle of the postero-external cusp. In m. .9 the structure is similar, so far as it is preserved, but tho talon is almost entirely broken away. Tho dimensions (in centimetres) of this specimen are : — Extreme length so far as preserved Length of symphysis Distance between end of process and alveolar border "Width of sympbysial region at f. 3 10-2 6- 3 7- 2 2-5 app. Tho dimensions (in centimetres) of the teeth are ; — Length. Width. pm.l 1-2 -7 jj?n. 2 1*2 ’9 pm. 3 1 ‘3 1 pm. 4 1‘3 I'l m. 1 1-5 1-1 m. 2 1-7 1-3 m. 3 ? 1-5 M. 8541. Plaster cast of the above specimen. Made in the British Museum. Geniohyus fajumeiisis, Andrews. [Plate XIX. figs. 2, 2 a.] 1904. Geniohyus fajumensis, C. W. Andrews, Geol. Mag. [.5] vol. i. p. 1G2. Type Specimen. — Portion of right ramus of mandible with the premolars well preserved (PI. XIX. figs. 2, 2 a); British Museum. This species is distinguished from G. mirus by (l)its larger size, the premolar series measuring 5'6 cm. in length ; (2) the main cusp being distinctly divided into an inner and outer tubercle in pm. 2 ; (3) the posterior lobe of the premolars being much larger and more distinctly selenodont. Form. & Loc. — ITuvio-marine beds (Upper Eocene) ; north of Birket-el-Qurun. M. 8435. Portion of right ramus of mandible with jvn. 1-4. Type specimen described in Geol. Mag. [5] vol. i. (1904) p. 162. Figured PI. XtX. figs. 2, 2 A. The first premolar (pm. 1) is strongly compressed, with a very small anterior tubercle, a high main cusp from which three ridges diverge posteriorly, one running down the outer face of the tooth, a second back to the anterior arm of the V-shaped posterior cusp, the third inwards down the inner face of the tooth. The posterior lobe is distinctly selenodont. In pm. 2 the anterior tubercle is larger, and the ridge running inwards from the main cusp has a small tubercle on its inner end. The posterior lobe is larger than in pm. 1. Pm. 3 has a still larger anterior tubercle and the cusp on the inner side of the main cusji is nearly as large as that element and clearly separated from it ; the posterior V is still larger. Pm. 4 is similar, except that the small anterior cusp is 2c2 19G TEETLAEY VERTEBRATA OF THE FATtTM. doubled, the posterior lobe still larger, and there are traces of a small postero-internal tubercle. The dimensions (in centimetres) of the premolars are : — Length. Width. pm. 1 1 -y '7 pm. 2 1-3 -8 2>m. 3 1’5 1 pm. 4 I'G 1'2 Length of ])reuiolar series 5-6. Geilioliyus major, Andrews. [Text-fig. 6o.] 1904. Gemohijus major, (J. W. Andrews, Geol. Mag. [5] vol. i. p. 212. Type Specimen. — Portion of loft ramus of mandible with y^m. 1-3 Geological Museum, Cairo. Text-fig. G3. Left lower premolars {pm. 1-^un. 3) of (I'enioJn/us major. f nat. size. (text-fig. 63) ; T'his species is considerably larger tlian either of the others, the length of the three premolars being 5'5 cm., while in G. mirus the same teeth measure 3’G cm. and in G. fajvmensis 4T cm. The posterior lobes of the premolars are still larger and more selenodont than in G. fajimiensis. Form, dt" Loc. — Fluvio-marine bods (Upper Eocene): P>irket-el-Qurun. C. 8980. Portion of loft ramus of mandible with pm. 1-3 in good })rcservation. The teeth (text- tig. 63) are very similar to those of G , fapiinen.ys,\n\i the hinder lobe is wider and more massive, .and in wear gives an even more distinct V-shaped surface. The dimensions ( in centimetres) of the teeth are : — Length. Width. pm. 1 1-8 1 jmi.'I l-'J 1-4 pm.‘^ 2 1-5 M. 8876. Plaster cast of the above specimen. Made in the Frillsh ^Intfenm. EOSIRKN. 107 Order SI REN I A. Family HALICORID.E. The occurrence of Sirenians in the Eocene beds of Egypt was first made known by Owen, wlio described a natural cast of the brain-case of one of these animals under the name Eotherium cegyptiacum This specimen was from the white Mokattam Lime- stone of Cairo, and therefore from a rather lower horizon than the Qasr-el-Sagha beds. A few years afterwards Filhol described f some teeth from the same limestone under the name Manatus coidomhi, which may be synonymous with Eotherium (egyptiacum. Lately much more information concerning Eotherium has been given by Dr. O. Abel, wdio, in his important memoir entitled “Die Sirenen der mediterranen Tertiarbildungen Osterreichs ” J, gives an account of some recently collected remains of this animal. This writer also proposes to publish shortly an exhaustive account of the remains of Sirenians both from the neighbourhood of Cairo and from the Fayum, so that in the present Catalogue it will only be necessary to give a short description of such remains as are preserved in the British Museum and in Cairo. All the specimens from the Fayum appear to belong to the genus Eosiren. Genus EOSIREN, Andrews. [Geol. Mag. [-1] vol. ix, (1902) p. 293.] Sirenia in which the three incisors and the canine are present at least in the upper jaw. The first pair of incisors are enlarged downwardly-directed tusks ; the second and third are small and probably lost early ; their alveoli are situated somewhat on the outer side of the rostrum close to the maxillo-premaxillary suture. Eotheiium is distinguished from the present genus in several important particulars, some of the chief of which are : — (1) the anterior incisors are not greatly enlarged and tusk-like, and the two other incisors, though situated far back in the premaxilla, are still large and placed on the edge of the jaw ; (2) the natural cranial cast on which this genus is based dilfers so considerably from a cast of the brain-cavity in Eosiren * Owen, Quart. Journ. Geol. Soc. vol. xxxi, (1873) p. 100. The generic name Eotherium had been previously employed by Leidy in 1853 for a genus of Perissodactyls, and therefore strictly the name Eotheroides suggested by Palmer (‘Science,’ n. s, vol. x. 1899, p. 494) should be employed for this genus, t Bull. Soc. Philomathique de Paris, ser. vii. vol. ii. (1878) pp. 124-5, t Abhandl. k.-k. geol. Eeiclisanstalt, vol. xix. pt. 2 (Vienna, 1904). 198 TEETlAllY YEKTEBKATA OF THE EATOM. that Dr. Elliot Sinitli is of opinion that tin ir generic separation would be justified by this difference alone; (3) the os innominatum is much less reduced and has a com- ])l('tely closed obturator foramen and a well-defined acetabulum with which a functional femur probably articnlated, whereas in Eosiren the reduction of the pelvis has proceeded almost as fixr as in Jlalitherium. Those particulars are taken partly from Abel’s paper above referred to, and j^artly from a skull and mandible of Eotherium recently acquired by the Geological Museum, Cairo : to this specimen further reference, with figures, is made below. Erorastomus'^ , another primitive Sirenian from the Lower Tertiary beds of Jamaica, differs from the present form both in the general shape of the skull, the slight deflection of the snout, the absence of enlarged anterior incisors, and in the form of the mandibnlar symphysis. Ilalitherium {P7'ototliermm)veronense,7A^xiO’\, approaches this genus very nearly, but in it the dentition seems to have already undergone considerable reduction. Eosiren libyca, Andrews. [Plate XX. figs. 1-7 ; text-figs. 64, 65, 68 B.] 1902. Eosiren liJo/ca, C. W. Andrews, Geol. Mag. [4] vol. ix. pp. 293-4, figs. 1-3. 1904. „ ,, 0. Abel, Abhandl. k.-k. geol. lleichsanst. vol. xix. pt. '2, passim. Type Specime^i. — A nearly complete skull described and figured, loo. cit. ; Geological Museum, Cairo. This is the type and only species of the genus at present known. Form. (& Loe. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. S/iitll (PI. XX. figs. 1, 1 A, 1 B ; text-fig. 64). — The type skull is not quite complete, the zygomatic arches and a portion of the basal region of the cranium being lost. The occipital surface is high and broadens out from above downwards. The occipital condyles {cond.) are larger and more prominent than in any other Sirenian skull with which comparison has been made, except Eother'nmi \ they are almost pcduncidate and their articular surface is strongly convex from above downwards and extends considerably on tlieir ventral face. In the mid-ventral line they are sc])arated by a deep rounded notch ; but it cannot be determined what share, if any, the basioccipital took in their formation, the sutures being obliterated. Above the foramen magnum the exoccipitals[exo.) meet in a suture about 2'3 cm. in length, thus completely excluding the supraoccipital from the opening; their upper ■* (^uart. Joiirn. Geol. Soc. vol. xi. (185")) p. 541. t /igiio, “Sireiiii fossil! trovati nel Veneto,” jMcid. 1st. Vencto (1. Sci. vol. xviii. (1875) ]>. 415; also by the same author, “ Quehjues Observations sur les 8irdiiiens i’ossiles,” Bull. Soe. geol. Franco, [3J vol. xv. (1887) p. 728, EOS] KEN Lir5rCA, 109 edges make an angle of about 1G0° with one another. The foramen magnum (/’.m.) itself is wider than high; its upper margin is deeply notched in the middle line, on either side of which the exoccipitals are produced into low tuberosities which overhang the opening. Laterally the exoccipitals are produced downwards into paroccipital processes, which resemble those found in the Dugong rather ttian those of the Manatee. The lower ends of these processes are about on a level with the lower border of the condyles ; their anterior face bears a vertical groove. Superiorly the anterior face of the exoccipital has a broad surface for union with the supraoccipital, and laterally a second for junction with the squamosals. The supraoccipital is roughly hexagonal in outline, the two lower sides uniting with the exoccipitals, between which the lower angle is thrust ; the lateral borders join the squamosals, at least in part, while the upper borders form the middle part of the lambdoidal ridge, being separated in the middle line by a prominence, from which a ridge runs down in the middle line, dividing the surface into two halves, each of which is slightly concave. In front of the lambdoidal crest the roof of the cranium formed hy i\\Q parietal s [pa.) is slightly concave both from side to side and from before backwards. In front of this the roof becomes concave from side to side, at least in the middle line, the borders being the somewhat prominent temporal ridges Avhich form the angles between the roof and the nearly vertical sides of the temporal fossse. The narrowest part of the skull- roof is about 6 cm. in front of the lambdoidal crest; at this point the width is 4‘2 cm., but behind this the roof widens slightly to its posterior border, where it measures about 5'5 cm. across. Anteriorly it widens out much more considerably, and at the post- orbital processes of the frontals it is 8'8 cm. wide. The sides of the cranium immediately in front of the occipital surface are somewhat rounded, but further forwards are nearly flat and, as already remarked, almost vertical : in this region the bone is thin, while in the middle of the skull-roof the parietals may attain a thickness of 1‘8 cm. The anterior part of the roof is formed by the frontals {fr.), and the shape of the suture between these bones and the parietals is shown in text-figure G4. Anteriorly they widen out to the large postorbital processes. Their anterior borders are notched by the comparatively large nasals {na.), between which they send a narrow process, which seems to have extended to the nasal opening, thus completely separating the nasals in the middle line. Outside the nasals (see text-fig. 64) the frontals are in contact with the upper ends of the facial processes of the premaxillm, which form the whole of the side and front border of the narial opening. The anterior angles of the nasals seem to be produced downwards along the inner side of the premaxillae till they meet the upper edges of the underlying maxillae. (See also Lepsius, llalitherium scliinzi, pp. 64-G6 *.) The maxilla [mx.) is a very large bone with a great antero-posterior extensio]i. * AbLimdl. d. Mittelrbeiiiischen geol. Yereins, vol. i. pt. 1 (Darmstadt, 1881). 200 TEETIARY VEiriEBlUTA OP TJIE EAYtjM. liilther ill advance of its middle point, and about beneath the anterior border of the orbit, its front portion is bent down, making an angle of about 140° with the posterior part. The alveolar border forms a double curve ; posteriorly it is convex outwards, so that the palate is much wider opposite the middle molars than at any other point. In the jiremolar region the border is concave outwards, so that the palatal surface is greatly narrowed, the narrowest point being about opposite the tooth here called the second premolar. In front of this the border thickens and turns outwards to the canine alveolus (c.), immediately in front of which is the maxillo-premaxillary suture. On the palate the maxilla extends rather further forwards, terminating as the posterior edge of Text-fig. 64. Middle portion of roof of sluill ol Eoslvcn llhi/ca- fr., fronfals ; na., nasals ; pa., parietals ; pmx., pretnaxillaj. f nat. size. the large median anterior palatine foramen {a.])f.). The tacial surface of the anterior part of the maxilla is nearly flat and vertical. Posteriorly it bears a broad shelt-like zygomatic prominence, which forms the floor of the orbit and is perforated in front by a large antorbital foramen. The j)remaxill; pseudosylvian depression ; t.J., temporal lobes. f nat. size. In Entherunn the general form of the brain is not unlike that figured, but the pseudosylvian depression is very slightly marked, so that the separation of the hemi- spheres into anterior and lateral lobes is obscure. 'J’he chief interest of the brain of Eosiren lies in its remarkable similarity with that of Ma'rithcrinm [vf. text-fig. 41, ]). 100). In both animals the hemispheres are divided in a quite similar way by the pseudosylvian deju'ession, and the cerebellum is relatively small. In Moerithermm^ as * Elliot Smitb, ‘Catalogue of the Physiological yeries. Museum, Coll. Surgeons,’ vol. ii. cd. 2 (lt)02) p. 311. EOS IREN LIRYCA. 203 might be expected in a land-animal, the olfiictory lobes are more developed than in Eosiren, bnt this does not affect the general similarity, which is the more striking when taken in conjunction with the many other points of likeness existing between the Sirenia and the I’roboscidea. It is interesting to note further that in the Middle Eocene forms of both these orders the brain is relatively large for mammals of that early date. In the terrestrial Proboscidea living exposed to many enemies, and in a complex and changing environment, this large development of the brain persists even in the modern types, and, indeed, their survival may be due to this very character. On the other hand, in the Sirenia, which early adopted a sheltered and sluggish mode of life, the conditions of which must have remained nearly constant, although there is some tendency towards increase in the size of the brain, there is no need for increased complexity, the result being the peculiar type of structure which Dr. Elliot Smith states can only be parallelled by the structure “ occasionally presented by the brains of idiots in which the process of elaboration has ceased in the earlier months of intra-uterine life, and the organ has simply grown in size without becoming perfected in structure.” Upper Dentition. — The dental formula of the upper jaw appears to be i. 2 or 3, c. 1, m.-\-pm. 8. At the anterior end of the downwardly turned rostrum there are the alveoli lor a pair of enlarged incisors (^. 1), which were oval in section and directed downwards and forwards ; the sockets are comparatively shallow, these teeth being apparently rooted. The only trace of the second incisors {i. 2) seems to be a small alveolar pit situated a little below and just in front of the third incisors {i. 3), which also are represented in this specimen by their alveoli only, these being placed immediately in front of the maxillo- premaxillary suture and on the side of the rostrum about 5 mm. above the sharp edge of the premaxillae. Both the second and third incisors are clearly on the way to disappearance, and seem to have been thrust outwards to the side of the jaw by the development of a horny plate covering the palatal and sharp lateral edges of the premaxillary region and replacing the teeth functionally. The canine alveolus {c.) is also small and on the side of the rostrum ; it is placed immediately behind the maxillo-premaxillary suture, and is almost in contact with the alveolus of i. 3. Behind the canine, and separated both from it and from one another by nearly equal intervals (about 1'3 cm.), are the sockets for four single-rooted teeth. In the type specimen only the last of these is in situ-, it consists of a comparatively small single cone with a very strongly developed internal shelf or cingulum. Immediately behind this come the relatively small quadrate two-rooted molars. There are four of these teeth, of approximately equal size. Each molar crown consists of two transverse ridges, each composed of two pointed cusps Avithout any secondary tubercles ; there is also a small anterior ridge or cingulum with a median cusp, which in wear becomes connected with the antero-internal main cusp. All the specimens 2 D 2 TEETIAEY VEETEBEATA OE THE FAYt^M. Ii04 iivailablo arc in bad ]n-oservation and further material is necessary before any detailed comparison with teeth of other genera is possible. SluH, of Eotherium. — I'lie skull and mandible of a ])rimitive Sirenian from the limestones of the Mokattam Hills has recently been acquired by the Geological Museum in Cairo and is important for comparison with Eosiren. The horizon from which these specimens come is lower than that from which the Fayum remains were obtained, and is probably the same as that in which was found the cast of the cranial cavity which Owen made the type of Eoth erhim (ogyptiacum. This skull and mandible Tnay in fact be referred to Owen’s species, though in some respects it differs from the brief description of some new material of that Sirenian lately published by O. Abel AVh en this author has |)ul)lished his complete account of the Egyptian Eocene Sirenia it will no doubt be possible definitely to determine these specimens ; meanwhile the fact that they represent a more generalized form than Eosiren, and are from a lower horizon in the same region, is sufficient to justify the comparison of the two types. The skull in question (text-fig. 66) is nearly complete, but the anterior portion has been compressed in such a way that the rostrum has been straightened, instead of bending down as, judging from the mandible, it must have done in the living animal; the anterior ends of the premaxillm have been separated by a fracture, the result of which is that this region has the appearance of having been more elongated than was actually the case. The occipital condyles are very large and are more sessile than in Eosiren ; in the mid-ventral line they are separated by a sharply defined notch. Eaterally the exoccipitaJs [exo.) are produced downwards into strong paroccipital processes {'pp-) which extend below the level of the condyles ; there is a large condylar foramen opening at the bottom of the groove between the base of the paroccipital process and the occipital condyle. The sutures between the exoccipitals and hnsioccipital [hoc.) are not ch ar, but that between the basioccipital and the hasispliciioid (hsp.) is marked by a transverse ridge, which crosses the basis cranii just behind the level of the ]iosterior edge of the veitical plates of tlie pferp/oids (pt.), which are closely united above with the basisphenoid. Above the foramen magnum (f ni.) the occipital surface is broad, much broader than in Eosiren, and somewhat like the same region \\\ Mceritherium [sog El. VIIE fig. 1 b). The snpraovci})ital [soc.) is gently concave from side to side; its upper border is greatly thickened and forms a great part of the massive lambdoidal ridge. In the middle line in front it thrusts a blunt triangular process between the posterior ends of the parietals ; laterally its upper angles form prominent backwardly directed bosses of bone, to the anterior face of which the parietals are closely united. The upper * “ Die Sireiien der niecliterraiK'n Tertiiirl>ilJuitgi'ii Oesicrreic-hs,’’ Abli. k.-k. gcol. Eeiclisaiist. vol. xix. pt. 2 (Vieniui, 1904). EOTTIERrUlNI yEGYPTIACUM. 205 posterior angle of the squamosal (sq.) is shut off from contact with the supraoccipital by a narrow posterior prolongation of the parietal which is wedged in between the two hones, somewhat as in Moeritherium. Beneath this ])oint there is a large fossa lying between the exoccipital behind and the squamosal in front ; this is occupied Text-fig. 66. Skull of Eollieriuin cFgyjytiacum (?) : A, from below ; B, worn surface of crown of first incisor ; C, from behind ; D, from above. «h, alisplienoid ; a.o.f., antorbital foramen ; a.p.f., anterior palatine foramen ; hoc., basioccipital ; bsg); basispheuoid ; c., canine ; cond.f., condylar foramen ; exo., exoccipital ; f.m., foramen magnum ; fr., frontals ; gl., glenoid articulation ; i. 1-3, incisors ; i.n., internal nares ; ju., jugal ; m. 1-3, molars ; mx., maxilla ; va., nasals ; nar., external nares ; pa., parietals ; per., periotic ; pi., palatine ; pm. 1-4, premolars; gim.v., premaxillse ; p.p., paroccipital process; pt., pterj’goid ; soc., supraoccipital; sq., squamosal ; tg., tympanic ; zyg., zygomatic process of squamosal. About 5 nat. size (except B, which is natural size). 20G TI<:KTIARY VEJITEBRATA OF THE FAYtJM. by the a])])arontly loosely united periotic {per.). The relations of the bones in this region seem to be very similar to those found in Manatus, except that in the latter genus the squamosal is not entirely cut off from contact with the supraoccipital. lleneath the ])criotic opening the post-tympanic portion of the squamosal unites closely with the anterior face of the paroccipital region of the exoccipital, and in front forms the posterior border of the external auditory meatus, the anterior boundary of which is constituted by the slightly developed postglenoid process. The articular surface {gl.) for the mandible is very broad ; it is slightly concave from side to side and gently convex from before backwards, except where it runs on to the slight post- glenoid ridge. The zygomatic process {~gg.) is very stout and is triangular in section ; it is underlain anteriorly by a slender prolongation of the jugal. The gmrietals {pa.) are large bones forming most of the cranial roof ; posteriorly, as already mentioned, they are separated in the middle line by a process of the supraoccipital, and laterally they send back processes which thrust themselves between the squamosal and supraocci})ital, and help to form the large prominences of the lambdoidal ridge. From the posterior angles of the bones a pair of not very well-defined supratemporal ridges run forwards, first converging slightly, then running parallel to about the level of the anterior border of the glenoid surface; in front of this they diverge considerably, and finally become continuous with the hinder edges of the postorbital processes of the frontals. Owing to the comparatively small development of the supratemporal ridges and also to the slight inflation of the cranial portion of the skull, the roof is not nearly so sharply marked off from the temporal fossiu as in the later forms, even in Eosiren. The ventral borders of the parietals unite with the squamosals posteriorly, then for a short distance with the upper end of the alisphenoid («/.), and in front of this again with the frontals, which they overlap in a squamous suture, running forwards in a sharp angle on tlie supratemporal ridges. The frontals (fr.) are very wide, forming the broad gently convex skull-roof in the region of the orbits, which they overhang as large supraorbital plates. Posteriorly they join the alisphenoid and in front of this their ventral edges seem to form the outer border of the groove for the optic nerve. Their anterior border is notched for the reception of the hinder ends of the nasals, between which they send a short triangular process. The nasals (w«.) seem to have been of considerable size, and overhung the narial o])ening {nar.) to some extent. The oj)ening itself is an elongated oval in outline, and its borders are formed by the nasals behind and by the ])rcmaxillae in front and at the sides. The ])remaxillary rostrum must have been bent down to a considerable extent, but in this s])ecimcn it has been straiglitened out by the pressure to which it has been subjected, and tlic end has been broken across tlie alveoli of the anterior incisors, 'flic u])])cr surface of the rostrum in front of the narial o])ening is gently concave from side to side. The maxilla {mx.) is a greatly elongated bone ; the anterior edge of its palatine region EOTIIEKIUM yEGYPTIACUM. 207 forms tlie posterior border of the large anterior ])alatine foramen (a.p.f.). Behind this the palate is deeply concave from side to side, but on either side is raised into a ])rominent ridge lying just within the alveolar border and extending back to the level of the alveolus of the tooth here regarded as 2. Behind this, the palate widens out, its greatest width being about opposite the front of m. 2. The transverse suture with the palatines is about opposite the i’ront of m. 1 ; the posterior palatine foramina are either very small or absent. On the outer side of the maxilla the broad zygomatic process rises by a very long base, and its ventral surface is very little above the alveolar border ; the antorbital foramen (a.o.f.) is smaller than in Eosiren. The suture between the jugal (ju.) and maxilla is not very distinct, at least posteriorly ; probably the relations of the two elements were almost as in Manatus ; at any rate, it is clear that the jugal made a broad squamous overlap on the upper surface of the zygomatic process of the maxilla, so that it forms the actual floor of the orbit. Behind this, it widens out suddenly, being produced downwards into a blunt point and upwards into a slight postorbital process. Posteriorly it becomes a mere rounded rod of bone underlying the zygomatic process of the squamosal. The palatines {pi.) form the greater part of the palate as far as the front of the molar series. The posterior border of the palate seems to have been a little behind the last molar, but in this specimen it is somewhat incomplete. The descending plates bounding the mesopterygoid fossa no doubt are formed by the palatines in front and the pterygoids behind, but tbe sutures are indistinct ; the same is the case with the junction of the lower part of the alisphenoid with the pterygoid. The body of the alisphenoid {al.) joins the parietals above, the squamosals behind, and the frontals in front ; its lower border forms the outer lip of a deep groove, at the bottom of which the optic and other foramina opened ; this groove is continued forwards to the orbit by the lower edge of the frontal. The orhitosphenoid is not distinct. The tympanic [ty.) is incomplete on both sides. The dentition in this specimen is of great interest. The dental formula seems to have been : i. 3, c. 1, y)ui. 4, m. 3, The anterior incisors are very remarkable teeth, and as in the later forms they are situated at the end of the snout, while they are already somewhat enlarged. They have very long roots, and their enamel-covered crowns are a little compressed from side to side ; the anterior border is rounded, the posterior sharp. The outer face is flat or slightly convex, while the inner is raised into vertical ridges, so that the worn surface of the tooth has the appearance shown in text-fig. 66, B, looking almost as if it were a complex tooth composed of several elements. The thick enamel has a peculiar appearance, owing to the development of numerous obscure wrinkles. Behind these teeth there is a diastema of considerable length separating them from the second incisors, which were large teeth situated on the edge of the premaxilla and not displaced outwards as in Eosiren. Immediately behind these were the third incisors, the posterior borders of the alveoli of which are in contact with the 208 TERI'IART VERTEBRATA OF THE FAYOM. anterior edge of the maxilla. The canine, which was about the same size as the incisors, is separated from i. 3 by an interval of about '7 cm. ; behind it again there is a diastema of about 2 cm. separating it from a single-rooted tooth, behind which again, and separated from it by a short interval, are four closely crowded alveoli. From the examination of this specimen alone, in which the teeth themselves are wanting or represented by their roots only, one would come to the conclusion that these four jmsterior alveoli belonged to the single-rooted 2, 3, and a double-rooted 4, as they have been marked in the figure ; but Dr. Abel, who has better specimens in which the teeth are preserved, states that in Eotherium the posterior premolars are single- rooted, and that there are in all six premolars, of which the second is lost very early. If this be so, then the alveoli znarked^jui. 4 in the figure belong to pm. 5 and 6 ; those marked pm. 2 and 3 to pm. 3 and pm. 4, while between the p>m. 2 and pm. 1 of the figure a tooth has been lost and its alveolus disappeared ; it may, however, be remarked that there is only a very short diastema behind pm. 1, while the interval between it and the canine is considerable, so that if a premolar has been lost at all it seems more likely to have been the first of the series. It is possible that the skull here figured may have come from a rather higher horizon than that at which Eofhermm proper is found, and that some modification of the teeth in the direction of the later forms may already differentiate it from the animal described by Abel; possibly it may belong to xibel’s new genus Profosiren*, at present undefined. Until that writer’s work on these Middle Eocene Sirenians is published, these questions mirst remain undecided. The molars are three in number ; they are bilophodont teeth, the anterior crest being formed by a large blunt inner cusp and an outer sharper portion composed of two obscurely separated elements. The posterior crest also consists of a blunt inner tubercle and a sharper outer one. From the antero-external side of the antero- internal cusp a ridge runs down to the cingulum, which forms a small shelf-like projection on the anterior face of the tooth : from the postero-external face of tlie postero-internal cusp a similar ridge runs down to the cingulum of the posterior end of the tooth ; this ridge is best developed in m. 3, where, with the main inner cusp, it gives a V-shaped surface in wear. This type of tooth agrees with the description given by Dr. Abelf of the primitive Sirenian molar, except that the intermediate cusp of the hinder row is very obscurely developed, if at all. The dimensions (in centimetres) of this skull are : — Extreme length (exaggerated by fractures) Width between outer angles of occipital condyles .... 8'2 Greatest width of occipital surface 13 Width ol foramen ma8) p. 442 ; also Ann. dcs 8c'. Nat. [2] vol. xi. ]). 27.] 'fiiird up])er molar wanting; first and second without antero-internal cusps; posterior lobe (metastyle) forming a cutting-blade larger than the anterior lobe, l^ow'er molars with neither jiostero-iuternal cus]) nor talon. * “ IStudii s of Eocene Mauuiialia iii (he Ahir.sli Collection, I’eabody Museuui," Ainer. .Jouni. ISci. [ I] vol xiii. (1902) p, 433. IlTyENODON.— PTEKODON. 219 This genus is represented by a single specimen only, consisting of the anterior part of a right ramus of a mandible with the alveoli of the large canine and the anterior premolars, the roots of the latter being in situ. Associated Avith this, and no doubt belonging to the same jaAV, is a third right lower molar. The crown of this tooth consists of tAvo high secant cusps, Avhich together form a cutting-blade: the posterior cusp is the larger and considerably the higher of the tAA^o. On the antero-external face of the anterior cusp near its base there is a small adherent tubercle ; there is no talon, though the cingulum is slightly developed on the posterior angle of the tooth. The outer face of the tooth is considerably Avorn, the direction of AA^ear being such that the cutting-edge remains sharp. This tooth is similar in general form to the last lower molar of the European species of Ilycenodon, especially in the presence of the small antero-external tubercle and the absence of the talon ; the posterior cusp, hoAvever, is shorter and higher than in the other species. This specimen seems to be sufficient to shoAV that remains of a Carnivore referable to the genus Hymiodon or some closely allied type exist in these beds, though insufficient to justify the establishment of a neAv species. Form. & Log. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. C. 8812-3. Fragment of anterior part of right ramus of mandible and a last loAver molar. The dimensions (in centimetres) of the tooth are: — Length 1'3, width ’7, height of posterior lobe IT. Genus PTERODON, de Blainville. [Ann. Fran^, et Etrang. d’Anat. et Phjs. a'oI. iii. (1839) p. 23.] 1885. IJemipsalodon *, Cope, Amer. Naturalist, vol. xix. p. 163. 1887. P seudopterodon *, Schlosser, Beitr. Fal. u. Geol. Oesterreich-Ungarns u. d. Orients, vol. vi. p. 201 ; also vol. \dii. (1890) p. 71. This genus has hitherto been recorded only from the Eocene of Europe. In the upper jaAV the third molar is small and transverselyeiongated. The first and second molars have an antero-external cusp, AA^anting in Ilycenodon, and the posterior lobe of the cutting-blade is smaller. In the lower molars there is no postero-internal cusp, but there is a small cutting-talon. M. 3 is much the largest. The jaAv is relatively short and heavy. Only one species at present knoAvn from Egypt. * Fide Matthew, Bull. Amer. Mus. Nat. Hist. vol. xiv. (1901) p. 20. 220 TERTIARY VERTEJ3RATA OF THE FAYOM. Pterodon africanus, Andrews. [Plate XIX. fig. 3 ; text-figs. G9-71.] It'O,”). Plerndo)! aj'r/rainis, ( !. W. Andrews, Geol. iMag. [4] vol. x. p. 342, fig. 3. S,j)ccimm. — Rigid ramus of mandible, incomplete posteriorly, with 2-4 and m. 1-3 well jweserved (PI. XIX. fig. 3) ; British Mnseum. '1 Ids species is distinguished from all the others by its much larger size. Form. cC* Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. M. 8503. Right rainns of mandible, wanting the ])osterior portion : pm. 2-4 and rn. 1-3 vi situ. Type S{)ecimen figured loc. cit. sitjo'd. The symphysis, which seems to have remained nnanchylosed throngli life, is very deep and long, extending hack to the level of the middle of ]>m. 3 ; its depth is largely dne to the enlargement of the front of the jaw resnlting from the great size of the canine tooth. Behind the .symphysis the ramus increases very little in depth from before backwards, in which direction its lower border is gently convex. On the outer face of the jaw, in addition to two small apertures in the thickened wmII of the canine alveolus (c.), there are three foramina; the smallest is in front beneath the ))Osterior half of pm. 2 ; the other two (m.f.) are larger ami are beneath the anterior lobes of pm. 3 and pm. 4 respectively. The last molar (m. 3) is much the largest of the cheek-teeth ; it consists of a ])air of high comprcsseil cusps which form a cutting-blade, the ])osterior lobe of which is con- siderably the higher and has a sharp keel-like ridge on its postero-internal face ; the small talon a])parently consists of a single cusp with a sharp median ridge. There is a small ])roj(‘ction on the antero-external angle of the tooth near its base ; this seems to belong to the cingulum, which is wanting elsewhere. The second molar (»?. 2) is similar to the first, except that the talon is relatively larger and forms a more distinct blunt edge, and the small antero-external prominence is also larger. The first molar (m. I) is mnch the smallest of the series ; the two main cusps, wdiidi are eonsiderably worn, are h‘ss compressed and form a less trenchant blade than in the other molars. The talon is similar to that of m. 2 and the antero-external projection is almost obsolete. The fourth premolar {jmi, 4) is much largx'r than the first mohu’ : it consists of a large, conical, sounnvhat laterally com])r(^ssed and backwardly directed cus]) with a cutting-edge; behind this there is a small talon also with a eutling-edge in the same line with that of the main cusj), and intc'rnal to it a slojiing sludf-like surface'. At tlue antc'ro-internal and postero-external angles of thee tooth tlu'iae are small tuberches belonging to thee cingulum, whidi is also slightly developc'd along the' whole' inner lae;e e)l the te)olh. I*m.?) is sinular te) pm.-\:^ esxeu'pt that the' main cus[) is ne)t se) high, the tale)n rather smaller, ami the ante-ro-inteiaial tube'rehi alme>st ab.-e'ut. Pm. 2 consists of a single cusp, of whieh thee anterieer shepe' is sheeideu’ than thee pe)ste'rie)r ; just a ti’acee e)t the tale)n is still to be seeen, /’m. \ is i’e'|)rcseente'd e)nly by its singlee neearly cireidar alveolus; all thee other jere'molars ami meelars are imjilanie'd by twe) reeeets. The alveolus of the canine (c.) sinews that that tooth was ve'ry lai’ge anel oval in se'ciion, the long axis be'ing PTEKODOX AERICANUS. 221 antero-postorior. There were three small iiieisors crowded together so as to form nearly a vertical row ; the smallest alveolus is on the actual edge of the alveolus o£ the canine. The dimensions (in centimetres) of this s[)ccimen are : — Total length of the specimen, so far as preserved 2.‘5-8 Length of the symphysis 8'G Depth of the ramus ojjposite the hinder end of tlie sympliysis . 5-5 ,, „ beneath Hi. 2 5-8 „ „ „ m. 3 5-7 Transverse diameter of the canine alveolus 2 app. Antero-posterior diameter of the canine alveolus 2'7 app. The dimensions (in centimetres) of the teeth are : — pm . 2 ji»)i. 3 j}m. 4 m. 1 m. 2 m. 3 . Length. Width. 2-3 11 2-6 13 2-6 13 2'1 10 2-8 14 3-4 17 C. 10192. Anterior part of a much-crushed skull in which pm. 2-4 and m. 1 are preserved on the right side and yu)i.3-4 and m. 2 on the left (text-tig. 69). On the left side the upper portion of the muzzle is preserved about as far back as the anterior border of the orbit, • from beneath which a strong ridge, probably continued from the zygomatic process, runs forw'ards on the side of the face, terminating just behind the large antorbital foramen (no./.), which is situated above p7?i. 3. The snout seems to have been broad and massive, and contracts a little in width jTist behind p?n. 2, but the whole is greatly fractured, so that it is not possible to be sure of its original form. The anterior part of the palate is concave from side to side and there is a })air of large anterior palatine (incisive) foramina {a.p.f.), elongate-oval in form and apparently situated between the canine alveoli. All the incisors and the canine are wanting, and their alveoli so crushed and imperfect that nothing can be said about them. Fm. 1 seems to have been a small, perhaps oue-rooted tooth. Of pin. 2 the hinder half is preserved on the right side ; it had a high laterally compressed conical crown, probably somewhat curved backwards, and there were two roots. Fni. 3 consists mainly of a high laterally compressed cusp ; it is narrower anteriorly than })osteriorly, there being a slight prominence at the postero-internal angle. There is a small tubercle on the hinder slope of the main cusp near its base, and this tooth has two roots. Fm. 4 is much larger ; it consists of a high conical backwardly-sloping cusp, connected with the hinder edge of which is a short cutting-talon ; on its inner anterior side there is a small keel-like prominence borne on a separate root ; there are three roots in all, two anterior and one [losterior. M. 1 is a large triangular tooth ; it consists of a large pointed main cusp, obscurely divided into two by a shallow vertical groove, and connected antero-internally with a small but distinct cusp borne on a separate root. On the antero-external face a small cusp apparently represents the pai-astyle, and posteriorly there is a large trenchant talon, the cutting-edge of which is on its inner side. iM. 2 is similar to m. 1 in structure, but larger. M. 3 cannot be made out, but it must have been a small tooth. The autero-iuternal angles of the first and second molars project 222 TEliTIAEY VERTEBKATA OF THE FATtTM. somewhat in advance of tlie hinder border of the tootli next in front ; there is a deep fossa for tlie recejition of the lower molar behind and to the inner side of rn. 2. The whole dentition, so far as ])reserved, is closely similar to that of Pterodon dasi/ttroulen, from which, however, this s[)ecies is distinguished by its greater size. The dimensions (in centimetres) of this specimen are : — Width of snout at level of canines 7 „ „ behind jun. 2 5-5 Text-fig. 09. Anterior part of skull of p.) Pterodon africamis : A, from riglit side ; B, from below, anterior palatine foramen; ao.f., antorbital foramen; ?n. 1-2, first and second molars; 2-4, second, third, and fourth premolars. On the right side the second molar lias been restored from that jireserved on the left. | uat. size. The dimensions (in centimetres) of the teeth arc : — Length. Width. pm. 2 2'4 app. ]‘2 pm. 3 2' I 1 '3 pm. 4 2-5 2 m. 1 2-9 2 m.2 3-0 2-3 Length from anterior end of yua. 2 to posterior end of m. 2, 13'5 app. PTEKODON AFRICANUS. 223 riio lollowing specimens are referred provisionally to this species : — C. 8898. Lelt linmerns, somewhat imperfect at proximal end (text-fig. 70). The head (/t.) is very strongly convex from before backwards, and less so transversely ; its surface looks nearly as much backwards as upwards. The outer tuberosity (o.t.) is massive and roughened, but it is broken away above, so that its height cannot be observed. The shaft is to some extent laterally compressed till just above the distal expansion. The Text-fig. 70. Left humerus of (?) Pterodon africanus: A, from front ; B, from outer side. d., deltoid crest ; en.f., entepicoudylar foramen ; h., head ; i.c., inner condyle ; o.c., outer condyle ; o.t., outer (greater) tuberosity ; s.jj., supratrochlear perforation ; s.r., supiuator ridge. | nat. size. deltoid crest {d.) is only moderately prominent, and extends down about two-thirds of the shaft. The supinator ridge (s.r.') is very slightly marked. The inner condyle (i.c.) is moderately prominent, and there is a large entepicondylar foramen (en.f.). Both the coronoid and olecranon fossae are large and communicate by a very large suj>ra- trochlear foramen (s.p.). The trochlear surface consists of an inner portion produced considerably downwards, a broadly rounded intercondylar ridge, and a narrower outer portion. The whole bone seems to resemble the humerus of the American species of 224 TERTIAEY YEHTEBRATA OF THE FAYDM. ] hlOiuodoii. :is descrilxMl by Scott*. The dimensions (in centimetres) of this specimen arc : — Length from top of liead 23-5 Y'idth of proximal end 7‘3 ,, middle of shaft (from side to side) 2 ,, ,, (from before backwards) .... 3 „ distal end 6app. „ „ articulation 4-3 M. 8886. J’histcr cast of the above specimen. Made in the British Museum. Text-fig, 71. Right femur of (?) Pterodon (ifricanus : A, from front ; B, from inner side. fl.t., greater trochanter; 7t., head ; i.l., inner tuberosity; 1.1. , lesser trochanter; n.l.i., notch for lujamenturn teres ; o.i., outer tuberosity ; t.l., third trochanter, h nat. size. C. 8897. Right femur, somowliat crushed at the distal (>nd (text-lig. 71). The liead {h.) is large, rounded, and jiedunculate ; on its jiosterior surface there is a deep notch or groove for the round ligament (n.l.t.). The great trochanter (ff.t.) is not veiy large, and does not rise '* Iscott, “Tlie Osteology of Ihjcenodon,” Journ. Acad. Nat. Sci. Bhiladelpliia, vol. ix. (1895) p. 513. Fl'EHODON AEKICANUS. — APTEEODON. 9, 9; (juite as high as the top of the liead. The lesser trochanter (l.t.) is a large prominence united with the great trochanter by a strong ridge, which forms the outer border of the deep digital fossa. The shaft is strongly compressed from before backwards, and broad from side to side ; on its outer side, about a third of its length from the j)roximal end, there is a rugose ridge representing a third trochanter (<.<.). The whole shaft is curved, the convexity being forwards. The distal articulation is very large. The rohilar trochlea is narrow and extends far up the front of the bone, as in tlui femur ol' Hyainmlon figured by Scott (Journ. Acad. Nat. Sci. Philad. vol. ix. p. 523). The tuberosities are large and project strongly backwards, the inner (i.t.) rather the furthest ; they are separated by a broad and deep intercondylar groove. In its general form, particularly in the broad flattened shaft, the bone suggests that the animal may have been to some extent aejuatic. It is possible that this femur may have belonged to Apterodon, or at least to the same animal as the humerus provisionally referred to Apterodon, since that bone also suggests possibly aquatic habits on the part of its possessor. The dimensions (in centimetres) of this specimen are: — Extreme length 23 2 Diameter of bead 3T Width of proximal end 7 „ mid-shaft 3-2 ,, distal end (j M. 8887. Plaster cast of tl le above specimen. Made in the British Museum. (ieiius APTERODON, Fischer. [Bull. Soc. Geol. France, [3] vol. viii. (1880) p. 288.] 1887. Dasyurodon, A. Andreae, Bericht Senckenberg. naturforsch. Gesellschaft, Frankfurt-a.-M. p. 12.5, j)l. iv. The specimens described below agree closely with the figures of the teeth of hasyurodon given by Andreae. Unfortunately, Fischer gives no figures of his Apterodon, which, from his description, differs a little from Dasyurodon ; but, since most authors regard the two names as synonymous, Apterodon is here adopted on the ground of priority. This genus is distinguished from Pterodon by the much slighter development of the cutting-blade of the lower carnassials, due to the smaller degree of compression of the cusps, and also to the much smaller size of the antero-internal cusp ; the talon also is relatively much larger. In these points Apterodon,m fact, seems to be intermediate between forms like Sinopa and Pterodon, just as the latter is intermediate between Apterodon and Hycenodon, in the latter of which the talon is almost obsolete and the two anterior cusps form a sharp secant blade. 2 G TICHTIAKY VKHTl'MiRATA OF THE FAYOM. Apterodon macrognathus, Andrews. [Plate XIX. figs. 4, 5 ; text-figs. 72—76.] 11)01. I’ti'rodoii nincroijiialluiK^ 0. W. Andrews, Geol. Mag. [5] vol. i. p. 211. Type Left ramns of mandible witli m. 1-2, jnn. 2-4, and the base of the canine (text-fig. 72) ; Geological Museum, Cairo. This si)ecics, as its name implies, is es])ecially remarkable for the elongation of the jawg particularly of the post-alveolar portion. This character furnishes a further distinction from Pterodo)), in which the mandible is comparatively short and stout. 'I'he dental formula is /. 3, c. 1, jim. 4, m. 3. The length of the molar-jn’emolar series is 0'7 cm., the total length of the jaw being 22 cm. Judging from Fischer’s description, A. yaudnji differs from the jU’esent species in being smaller, in the smaller size of the antero-internal cusp of the molars and of the posterior tubercle Text fig. 72. Left ramus of mandible of Apterodon niacroffiuiihus, type specimen, from inner side. anp., angle of mandible ; <■., canine ; cond., condvle ; d./'., opening of dental canal ; i. 1-3, incisors ; m. 1-3, molars; pm. 1-4, premolars ; .sn/ni,., symphysis, g nat. size. of the last premolar. Apterodon [Dasynrodon) Jlonheiniensis, AwAvqac, sp., is strikingly similar to the present species, but tlie main cusps of the molars are rather lower and blunter, and the talon is shorter. Form. (P Loc. — Fluvio-marinc beds (Upper Eocene) : north of Pirket-el-Qurun. C. 8982. ramus of maiidilde witli »>. 1—2, /nn, 2-1, and base of caniiu' in .'fitii. I’ypo .specimen, described in Geol. Alag. lor. rif. .‘oijiru ; ligniaMl iti t(nxt-flg. 72. I'ln^ sympliysi.s pi/ni.) is dee]) and ext('nd(‘d back to benealli flic third |)remolar. The mandibular ramus is narrow from above d<)wn\\ards and ju’oportionately" very long ; the vcmtral boiabu' is nearly straiglil. The length ol the jaw behind the alveolus ol the last molar is V('ry gia'at. The coiuhle (cond.) is (olindrieal and elongated li'om sid(' to side; it is on the same level as the alveolar border. I'he angrdar region {(inp.) is sejiarated Irom the A ri'EliODON iMACKOGNA'l'IlUS. 227 condyle by a deep notch and is slightly inflected. The coronoid process is incoin[)lete. The dental canal (d./.) opens low down near tlu* ventral border. On the outer face of the mandible there are four or five foramina., of which the most anterior is beneath the alveolus of 1, the next beneath the middle of pm. 2, the third and fourth beneath the front and hinder roots respectively of pm. d. The third molar is represented by its alveolus only. The secoiul consists of a high anterior portion and a large talon with a blunt cutting-edge. The anterior portion consists of a large posterior cusp with a much smaller one closely united to its antero-internal side, the two together forming a very blunt and imperfect blade ; in Pterodon and Ilpoinodon the antero-internal cusp is enlarged and secant, and with the posterior cus[) forms the powerful cutting-blade of the carnassials. There is no trace of a postero-internal cusp. The first molar is much smaller than m. 2 ; it is greatly worn, particularly on its antero-e.Nternal face. The anterior half of the tooth is composed of a small antero-internal cusp (paracone) and a larger main j)osterior cusp (protocone). The talon consists of an outer cusp and a lower inner ridge ap})arently continuous with the cingulum. The fourth premolar is much larger than ni. 1 ; it is composed of a large stout main cusp and a small talon. The second and third ])remolars are simple com[)ressed cones, each borne on a pair of relatively large roots. In both premolars ami molars the cingulum is well marked. Pm. 1 is re])resentcd by its alv(‘olus only; it seems to have been a one-rooted tooth squeezed outwards between the hinder edge of the canine in front and pm. 2 behind. The canine is relatively large, and there are three incisors so crowded together that one, probably i. 2, is displaced so as to lie above and behind the other two. The dimensions (in centimetres) of this specimen are : — Total length of the jaw 22 Depth of ramus at hinder end of symplly.^iN d'2 ,, „ beneath m. 3 3'2 Length of symphysis o'S Width of condyle 2‘3 Distance between hinder border of the alveolus of wi. 3 and the posterior angle of the condyle 10'2 Autero-posterior diameter of canine 2 The dimensions (in centimetres) of the cheek-teeth are: — Length. Width. «i. 3 (alveolus) la; m.2 TO ’SJ vi.l 1-2 -7 pm. 4 1’7 1 pm.‘d TI -9 pm. 2 T2 '7 M. 8880. Tlaster cast of above specimen. Made in the Briti.dL Museum. C. 8815. Tosterior portion of right ramus of mandible with m. 1-3 in ])crfect jtreservafion (text- fig. 73). The description given above of the second molar in specimen C. 8982 applies equally to m. 2 and m. 3 in this mandible. It can, however, be seen that the cingulum 2g 2 228 TERTIARY VERTEBRATA OF THE FAYlTM. is strongly developed on the inner side of the cutting-talon, which is slightly notched in the middle. The talon of m. 1 is composed of an outer cusp, a very small posterior and a rather larger inner tubercle belonging to the cingulum, the three surrounding a shallow depression. The dimensions (in centimetres) of the teeth are : — Length. Width. w. B 1-9 1 yn.2 1-8 '9 mA FB -6 M. 8873. Plaster cast of the above specimen. Made in the British Mnseyim. M. 8437a. Portion of right ramus of mandible with greatly worn and broken cheek-teeth. M. 8437b. Portion of right ramus of mandible with pm. 2 and 3 complete, the other cheek-teeth broken and worn. Figured on PI. XIX. fig. 4. M 8436. Posterior portion of right ramus of mandible with ?n. 2 and m. 3. fig. 5. Text-fig. 73. Figured on PI. XIX. I’ortion of right ramus of mandible of Apterodon macrotjnatlms ; A, from above ; B, from outer .side. pm. 4, fourth premolar; m. 1-3, tlie molars. | nat. size. The following specimens are referred provisionally to this species : — M. 8439. Nearly complete axis vertebra. In this vertebra the centrum is very mnch depre.ssed ; anteriorly its ventral surface is concave from side to side, but posteriorly there is a median keel terminating behind in a hypapophysis. The odontoid is much llatteneil dor.so- ventrally ; its ventral surface for the atlas is limited posteriorly by a sharj) ridgi'. Tbe lateral surfaces are about as deep as wide, their ventral borders being j)roduced downwards considerably below the ventnd surface of the nist of the centrum. The backwardly directed transverse [)roce.sses are largo and long, extending considerably behind the ])osterior end of the centrum ; the verh'brarteria! canal is small. The neural canal is both wid(! and high. The neural spine is a v('ry high hatehet-shaped plate projecting considerably backwairds behind the rest of tlu' vertebra ; its [)ost('ro-ventral bordi-r is much thickened. The posterior zygapophy.ses are massive projections, their APTEEODON MACROGNATIIUS. 229 articular surfaces being oval iii outline. The dimensions (in centimetres) of this vertebra are : — Ijeiigtli from top of odontoid to posterior face of centrum . . 6-(5 VVidtli of anterior articular surface of centrum 5 ,, posterior articular surface of centrum 2-‘J I leight to top of arch ti’Tapp. Width between outer ends of zygapophyses 4'7 Text-fig. 74. Left humerus of (?) Apterodon macrognatlius : A, from front ; B, from outer side. h.g., bicipital groove ; d., deltoid crest ; en.f., entepicondylar foramen ; /«., head ; i.c., inner condyle; i.t., inner tuberosity ; o.c., outer condyle ; o.t., outer (greater) tuberosity ; s.r., supinator ridge. 4 nat. size. C. 9445. Left humerus (text-fig. 74). The head (/«.) is strongly convex and greatly elongated from before backwards ; it looks as much backwards as upwards, while from side to side it is narrow and not very strongly convex. The outer tuberosity {o.t.) is high and somewhat compressed, its outer face is flattened, the inner concave. The inner tuberosity (i.t.) is a massive prominence with a flattened end ; between it and the outer tuberosity is a deep bicipital groove (b.g.). The shaft is very strongly compressed laterally and the TERTIAHT VERTEBKATA OF THE FATfJM. rioO deltoid crest (d.) is enormously developed, forming tlie strongly convex sharp anterior edge of threc-rourllis of the length of the shaft. The supinator ridge (s.r.) is greatly developed as a sort of scroll-like flange which projects very strongly ])ackvvards as well as outwards. The inner condyle {i.c.) is very prominent, and there is an ente{)icondylar foramen {en.f.). The coronoid fossa is small and shallow; the olecranon I'ossa is also small, hut sharply defined ; there is no suf)ratrochlear perforation. The distal articulation consists of a prominent inner portion, projecting below the rest of the surface, a gently rounded intercondylar ridge, and a narrow outer surface deeply notched distally as in Lufra. On the whole, this humerus is \ erylike that of Lutra and Text-fig. 75. A. B Itight tibia of (?) Apterodon macrognatlnis, lacking epiphyses: A, from inner side; E, from front. cn.. cnemial crest ; ?»(., ao', deep impressions for muscle-attachments, j nal. size. still more like that of Poiamoihn 'imn, so that it is ])0ssihle that the animal to which it belonged may have lived a semi-a(piatic lile. The dimensions (in centimetres) ol this sp(*cimen are : — Length (from toj) of great trochanter) -1 Width of proximal end 5-8 „ middle of shaft (from side to side) Id! ,. „ ,, (from before backwards) .... 8\S .. distal end ba} ,. „ articulation M. 9257. 1 Taster cast of the above specimen. Mtule in the lintifli Mnseum. A PTEliODON MACIiOQNATIIUS. 231 M. 8504. Distal end of right luiiuerns. Figured on PI. XIX. figs. 7,7 a. Closely similar to C. 0445. M. 8440. Distal ends of two similar linmeri. C. 8845. Right til)ia, wanting the epiphyses (text-fig. 75). The bone, as a whole, is strongly curved, the convexity being anterior. The cnemial crest (ca.) slopes away and probably its upper end was overlapped by the patella. It extends about halfway down the bone, and terminates in a rugose prominence for the attachment of a ])owerful muscle. The upper half of the shaft is trihedral. On the inner face just below the ujijxu- end there is a long roughened depression for muscle-attachment (m.). The postei'ior face at the uppei- end of the bone is concave from side to side. Towards the distal end the shaft widens out a little, but in this specimen the articular region is wanting. On the whole, this bone seems to lend some support to the idea that this Creodont may have Text-fig. 7 produced backwards and inwards into a considerable prominence. The neck is long and is directed more inwards than usual in the true Carnivora ; the head bears two facets, a large terminal gently convex surface for the navicular (nav.) and a small surface looking outwards and making an obtuse angle with the last; this (cal.) is jirobably for contact with the distal end of the calcaneum or perhaps with the cuboid. The (dongated ectal facet (ect.) is placed very obliquely to the dorso-plantar axis ; it is slightly concave [)Osteriorl3- and flat in front. It is sharply bounded on both sides by deej) fossse, that in front separating it from the sustentacular facet and having at its posterior end the ventral opening of the astragalar canal. The sustentacular facet (.. 12G. 1874. Protolomus, Go])Q, Report on Vertebrate Fossils obtained by the Wheeler Expedition in New Mexico, p. 13. TTiis genus includes small or medium-sized Cieodonts, in the mandible of which the first molar is the smallest of the series. 'The lower molars consist of a high anterior SIXOl’A ETIIIOL’ICA. Zoo blade and a small talon. 'I'lu' liigh anterior portion consists of an antero-intci nal and a postero-external cnsp, wliicli tend to form a cutting-blade, and a small })ostero-internaI cusp. The tabm in the typical species is more or less basin-sha])ed. It is with considerable hesitation that the fragment of a mandible described below has been referrc'd to a member of this genus, wdiich has hitherto been almost, if not quite, confined to North America, 'flie European genera and /Voy/eerm are very closely allied to Sinopa^ Imt tlie present specimen difhu’S from the mandibles of species referred to them both in being considerably larger and in possessing more massive molai>, the cusps of which are neither so high nor so ])ointed. lliitimeyer * has already referred a small Creodont fi om the Eocene of Egerkingen to Stijpolophas [Sinopa), distiiniiiishing it from Proviverra and Cpnohijce.iiodon on these same grounds, and his specimen must be very similar to that now described and made the type of a new species. Sinopa etMopica, sp. nov. [Plate XIX. tigs. G, 6 A.] Type Specimen — Portion of left ramus of mandible with pm. 4 and m. 1-3 in situ (PI. XIX. figs. 6, 6 a) : Geological Museum, Cairo. This species is about the same size as Sinopa agilis (Marsh), but differs from it, and apparently from the other American species also, in the relatively smaller size of the last premolar and fir^t molar compared with the last molar. It also differs from the typical members of the genus in having a trenchant talon, the cutting-edge of which is situated rather towards the outer side of the tooth ; in the other species the talon is basin-shaped. This difference suggests that when more is known of its structure, this species may requiri' to be placed in a nevv genus. Form. & Log. — Fluvio-marine beds (U[)per Eocene): north of Birket-el-Qurun. C. 10193. Portion of the left ranuis of the mandible with the somewhat broken molars and fourth premolar. Type specimen figured on PI. XIX. figs, fi, 6 a. The 1 amus, so far as preserved, is of nearly the same depth throughout ; posteriorly it is broken away about 1’5 cm. behind the last molar ; there seems to have been a well- marked masseteric fossa. The last premolar (p»i. 4) consists of a large, somewhat, compressed, main cone, v/ith small anterior and posterior basal cusps, the posterior one being the smaller and forming a short cutting-talon ; the basal length of this tooth is a little greater than that of m. 1. The molars increase in .size from before backwards. Each consists of a high tricuspid anterior portion and a talon. In all the teeth the end,s of the main cusps have been broken away, but it can he seen that the postero-external cusp was the largest and with the antero-internal formed an imperfect cutting-blade ; the postero-internal cusp is small and intimately connected with the inner face of the * Abhandl. Schweiz. Pal. Ge.s. vol. xviii. (1S91) p. 104, pi. vii. figs. 10, 11. 2 II TEl{TIA]iY A^EETEBEATA OF THE FAT^M. 1^34 l:irp;c ])ost(M'()-oxteriKil cusp. The talon is of inoderate size, and its outer border is high and forms a cutting-edge; it is separated from the much lower inner border by a slightly concave surface, which is homologous with the basin-shaped depression of the talon in the other species. On the antero-external angle of the tooth there is a well- marked tubercle (stylid) belonging to the cingulum, which is wanting round the rest of the crown. The dimensions of this specimen are : — Length, so far as preserved, 4'G cm. ; depth of ramus beneath in. ‘i, 1'6 cm. The lengths of the teeth are: — pm. 4:, 8 mm. ; rn. 1, (3’5 mm.; m.2, 8'5 mm. ; 3, 11 mm. M. 9260. Plaster cast of the above specimen. Made in the British Museum. Order CETACEA. Suborder ARC II ^OGETI. Earaily ZEUGLODONTIDvE. Facial region of skull greatly elongated ; external nares opening comparatively far forwards ; nasal canal prolonged backwards by the union of tlie maxillae, palatines, and ])terygoids, so that the internal nares are far back; nasal bones elongated; frontals forming broad supraorbital processes. Parietal region of the skull very narrow, and temporal fossae very large. In the earliest forms (Protocetus) the normal eutherian dentition seems to have been present, and the teeth behind the second premolar have three roots. In the later forms [Zeuglodon) the dentition is reduced, probably by loss at the hinder end of the series ; the anterior premolars may have one or two roots, but the other teeth of the molar-premolar series are two-rooted, and have compressed crowns with sharp serrated edges. The iieAv genus Frozcuglodon described below is intermediate between these two types. The Zeuglodonts of the Fayum are especially interesting, because the first mammalian bones described from this region "were })arts of the skeleton of a member of this family. In 1879 Schweinfurth collected some vertebne, including an axis, from the island Geziret-el-Qorn in the lake l>irket-el-(.Iurun : the beds in which these remains were found belong to the Pirket-el-Qurnn series of Peadnell, forming the upper part of tlie Lower Mokattam beds. The s])ecimens were described by Dames*, by whom they were referred to three forms: — (1) a large species with *- Sitzun^sb. k. preuss. /Vkad. Wiss. vol. i. (ISSb) p. 121). ZEUGLODONTIILE. elongated dorsal vcrtc'bne, referred to as “ species major” and said to be similar to the ZeiKjlodoii macrospoiid^liis of J. Midler ; (Ll) a smaller form with short vertebra:, resembling i\\c Z. brachijsponclijlns of Miiller and referred to by Dames as “ species minor”; (3) a still smaller species represcntc'd only by a few vertebrae, which are said to resendjle some vertebrie regarded by Muller as belonging to a young individual of Z. hrachyspondylu.s, but in the light of recent discoveries may more probably be referred to Z. Osiris or a closely allied species. Somewhat later Schweinfurth collected on the mainland near Qasr-el-Sagha (see map in Introduction) some further remains, including portions of the premaxillae and a nearly complete ramus of the mandible. These specimens were described in detail by Dames who founded upon them, especially upon the mandible, the species Z. oshis. Further material, including a fine skull and mandible of Z. osiris, was collected in 1902 in the neighbourhood of Qasr-el-Sagha by Drs. Stromer and Blanckenhorn, the former of whom has since published an exhaustive memoir f on these remains, referring most of them to Z. osiris, but some to a smaller form to Avhich the name Z. zitteli is given. This writer also compares the Egyptian Zeuglodonts with those of other localities and discusses the relationship of the group. Dr. Elliot Smith J has given an account of natural and artificial brain-casts from the same region, and concludes that probably two genera were present ; he also discusses the probability of the relationship of the Archenoceti to the true Whales, and considers that on the whole the brain-structure is in favour of the usual classification. Eecently Dr. E. Fraas § has described a skull of extraordinary interest from the bottom of the Eower Mokattam series of Cairo (corresponding Avith the Wadi Eayan series of Beadnell). This specimen has been made the type of a iieAv genus and species, Profocetus afaviis, and is remarkable as combining a skull Avhich is typically Zeuglodont in general form Avith a dentition which is practically that of a Creodont. The dental formula is : i. 3, c. 1, pm. 4, m. 3. The premolars and molars have not the peculiar serrated form characteristic of Zeuglodon ; pm. 3, 4 and m. 1-3 have three roots and indications of an inner cusp. There can be no doubt that Fraas is correct in regarding this type as an annectant form betAveen the Zeuglodonts and the Creodonta, but, although the origin of the Zeuglodonts is thus made clear, it still seems to be by no means so certain as that author belieA'es, that they may not themselves be the ancestral forms of the Odontoceti. Of the material iioav to be described the most important is the skull of a Zeuglodont discovered by Mr. PI. J. L. Beadnell in beds of the Birket-el-Qurun series, and * PalaBont. Abliandl., n. s., vol. i. (1894) p. 189. t Beitr. Pal. u. Geol. OesteiTeich-Ungarns u. d. Orients, vol. xv. (1903) p. G4. See also Sitzuiigsh. matli.-pliys. Cl. k. bay. Akad. Wiss. vol. xxxii. (1902) p. 311, and Zeitsebr. deuLseli. geol. Gesell. vol. 50 (1903), Protokolle, p. 36. t Proc. Boy. Soc. vol. 71, 1903, p. 322. § Palseout. Abhaudl., n. s., vol. vi. (1904) p. 199, pis. x.-xii. 2 II 2 23G TERTIARY VERTERIiATA OE THE FATtlAI. i heveforc intermediate Lctween tlie horizons of Vrotocetus atcmis and Zeuglodon odris\ as might he expected, it exhibits some interesting transitional characters in the teeth. Another specimen from the same horizon is a largo mandible here described as the type of Zettglodon ids. From the remains of Z. osiris collected by Mr. Beadnell and myself in the (iasr-el-Sagha series it is not possible to add anything of importance to Stromer’s detailed descriptions. Genus ZEUGLODON, Owen. [Load. & EJiiib. Phil. Mag. (3) vol. xiv. (1839) p.'302.] 3 1 4 2 Dental formula ; — ?. ^ ; c. j- ; pm. ^ ; 7n. 2^ 3 • Teeth with not more than two roots. C’heek-teeth with a laterally compressed crown — that of the premolars always strongly serrated on both edges, that of the molars serrated on both or only on the posterior edge. Zeuglodon osiris, Dames. [Plate XX. tigs. 8, 8 a ; text-tig. 77.] 1894. Zeuglodon i oslri h’, W. Dames, Paloeont. Abhandh, n. s., vol. i. p. 204, pis. xxx., xxxi., xxxiv.- xxxvi. 1901. G. W. Andrews, Geol. Mag. [4] vol. viii. p. 437. 1902. 99 E. Stromer, Sitzungsb. math.-})]iys. Cl. k. bay. Akad. AViss. vol. xxxii. p. 345. 190;h 99 99 E. Stromer, Zeitschr. deut.sch. geol. (lesell., Protokolk', vol. 55, ]). 37. 1903. 99 99 G. Elliot Smith, Proc. Poy. Soc. vol. 71, ]>. 322. 1903. 99 99 E. Stromer, Beitr. I’al. u. Geol. Oesterreii h-Ungarns u. d. Orients, vol. xv. ]). (15, ])Is. viii.-xi. 1904. 99 99 E. Eraas, Palmont. Abhandh, n. s., vol. vi. p. 199. Ttjpe Specimen. — Portions of premaxilhe, left ramus of mandible, and some vertebra}, described and figured by Dames, tom. cit. 1804, ])[). 101-204, ])ls. xxx., xxxi., xxxiv.-xxxvi. ; Itoyal Museum of Natural History, Px'ilin. In this species the dental formula is: i. c. | m. The first ])reni()lar is one-rooted. Molars crowded together. The su])raoccipital surface is narrow and very deeply concave from side to side, owing to the turning backwards of the sides of the ])rominent hirnbdoidal crest (see PI. XX. fig. 8). For detailed description of th(> skull and mandible, see Stromer’s memoirs referred to above. Form, tf' IjOC. — (Jasr-el Sagha beds (Middh' Eocene): north of Biiket-el-(2iirun. ZEUGLODON OSIKIS. 237 C. 10018. 1 ’oitions of :i soinewliat distorteil skull, inclu(liii;r (ho occipital rogioti and most of tlio roof as far forwards as the posterior portion of the nasiils. Figured on PI. XX. tigs. 8, 8 a. The cast of the cranial cavity is described and figured by Elliot Smith in Proc. Hoy. Soc. vol. 71, 1908, ])p. 322-o81, tig. 2. This specimen, so far as it goes, seems to resemble closely that figured by btromer, but is slightly larger. The occipital condyles (cond.), which project considerably, are relatively small ; they are widest at their upjier end, and are strongly convex from above downwards, but much less so from side to side. The exoccipitals (rao.) appear to meet in the middle line above the foramen mao-num, makintr a suture with one anothei' about 2'5 cm. long. The supraoccipital (soc.) is deeply concave from side to side, owing to the great size of the backaardly directed lateral portions of the lambdoidal crest {l.c.), of which it forms the posterior face, the anterior being constituted by the expanded posterior portion of the parietals (pa.), which unite with the supraoccipital in a very deep suture, the outer line running along the edge of the crest. In front of the lambdoidal crest, the upper part of the parietals forms a very high, sharp, sagittal crest (s.c.) extending as far as their junction with the frontals, which is about 5 cm. behind the great supraorbital expansions of those bones. Laterally, the posterior portions of the parietals form part of the very slightly convex cranial walls, and unite with the squamosals in a suture running downwards and forwards. The squamosals (sq.) are very large, and their upper surface is convex from before backwards ; they form a, considerable part of the cranial wall. The zygomatic process (zyg^) is large, and from its upper edge a ridge runs upwards and becomes continuous above with the lambdoidal crest, forming with it the posterior boundary of the enormous temporal fossa. The glenoid surface is wide and concave from before backwards ; there is a fairly well-developed postglenoid process. The frontals are incomplete, but it can be seen that they formed the great supraorbital expansion usual in the genus. In front they are separated by the nasals (na.), which are thrust between or over them, and terminate behind in a sharp median angle. Of the nasals only the posterioi’ portion is preserved : together they are convex from side to side and project a little above the rest of the surface of the snout. The whole of the front and base of this skull is wanting. The approximate dimensions (in centimetres) are: — Width at zygomatic processes 32 „ of occipital surface 22 „ „ condyles d'7 „ of foramen magnum 3 lleiglit of occipital surface above foramen magnum .... 13‘5 Length of sagittal crest of parietals 13 Greatest width of nasals -I'S M. 8150. Plaster cast of the above specimen. Made in the British Musetm*. M. 8150 a. Plaster cast of the cranial cavity of the above specimen. Figured Proc. l\oy. !Soc. vol. 71 (1903) p. 325, fig. 2. Made in the British Musenm. C. 10207. Left ramus of mandible wanting the angular and articular regions (text-fig. 77). Thi^ specimen is almost exactly like that de.scribed and figured by Dames (Palmont, Abhandl., n. s., vol. i. p. 191j pi. XXX.) in his original description of this species. In addition 38 TEETTAET VEliTEEIiATA OE THE EATIjM. to tlio loss of ilio post('rior yiortion, the inner wall of the dental canal has been crushed in, and tlie anterior alveolus is incomplete. The symphvsial surface extends back as far as the liinder border of p)n. 2. The sino'le alveoli of the incisors, the canine, and the first premolar are empty; they are separated from one another and from pni. 2 by almost equal int(>rvals of about 2'i cm. Pin. 2 is a two-rooted tooth, comywessed and sliarp-edeed, with two accessory denticles on its posterior border ; pni. 3 is represented by its two alveoli only ; 2>m. 4 is a large two-rooted tooth apparently having three accessory denticles on both its anterior and posterior borders. The molars are smaller teelh closely crowded together. In all, the anterior border is nearly verlical and without denticulations, while the ])()sterior border has two or perhaps three accessory denticles in )n. 1 and /». 2, and at least three in ni. 3. The crowns of all the Left ramus of mandible of ZcvgJodoii osn’is: A, from outer side ; B, Irom above, r., alveolus of canine; i. 1-3, alveoli of the incisors ; in. 1-3, molars ; jm. 1-4, premolars or their alveoli ; sy»i., symphysis. | iiat. size. teeth are somewhat obscured by a coating of gypsum. There are depressions foi the reception of the points of the uyiper teeth behind and rather to the outer side of the alveoli of 3, c., jmi. l,and almost iminediatidy bidiind the alveoli ot you. 2 and pm. 3. The dimen.‘-ions (in centimetres) of this spi'cimen are givim Ixdow' ; those ot the .specimens dc'scribed by llaines and Stromcr ari' placed in the second and thiid columns for compaiison : — Length from anterior end of jaw to antm-ior liorder of jmi. 2 . bord(>r of^iw. 2 to hinder border of Height of jaw beneath '.2 ]nn . 2 w. 3 . Length of the .syinpbysial surlace . J):mips’s type Stromer's spcciinon. ppoeiiucn. 24 22 a|>p. 2r> 24-.') 21 23-r) 3-.') 3 3-8 (>•7 4 ’5 .')-8 1 1 app. 28 r!l 1 1 f) ZEUGLODON OSfRIS. 239 Tho dimensions (in centimetres) o£ the teeth (or their alveoli) are : — ■ i. 1 (alveolus only) Length. ... 2-2 Width. Height. — ,, ... . . . 25 1-fl • . i. 3 ,, ... . . . 2o 1-5 c. 1 „ ... . . . 2-9 1-5 j)m. 1 „ ... ... 2-9 1-4 . . pin. 2 . . . 8-8 1-9 36 pm. 3 (alveoli only) ... 5 pm. i ... 5-2 2-5 5 ... 3 2-5 ... 2-8 2-5 3-9 ... 3-2 2 5 Some of the above measurements of the teeth are probably somewhat in excess of the truth, owing to the presence of a coating of gypsum. M. 9264. Plaster cast of the above specimen. Made in the British Museum. The following specimens are referred provisionally to this species : — • C. 10055. Five caudal vertebrae. In these the epiphyses are fused to the centrum, which measures in length 7‘5 cm., in width 7'7 cm., in height 7 cm. The neural arch, enclosing a very small neural canal, is situated on the anterior half of the centrum. There are broad transverse processes, the bases of which are perforated by a foramen. There seem to have been no vascular foramina on the ventral face of the centrum, which bears at its hinder end a pair of facets for the chevrons. C. 10051. Six associated vertebrae, similar in general form to the last, but belonging to a much smaller animal, the length of the centrum in the largest of these specimens being only about 5 cm. C. 10309. Four posterior lumbar and anterior caudal vertebrae, closely similar to the specimens figured by Uames {loc. cit. 1894, pis. xxxv., xxxvi.) and referred by him to Z. osiris. The ends of the centrum are slightly concave, the epiphyses being fused. The neural arch has a pedicle extending over three-fourths of the length of the centrum. The transverse processes are large and directed downwards and backwards ; in the caudal the base of the process is perforated. In the lumbars the ventral face of the centrum is concave or only very slightly convex from side to side ; in the middle are two large vascular foramina separated by a narrow bar of bone ; there is also a foramen (or a pair) in the floor of the neural canal. In the caudal vertebra there seem to have been large facets for the chevrons. These specimens are from the Birket-el-Quruu beds. The dimensions (in centimetres) of the centra of these vertebrm are : — Lumbar. Caudal. a. b. c. Length 6‘7 6-8 app. 6'7 Width 8-5 8"J 8 Height 7'5 7-4 7 app. TI'lRTIAIiY VEKTEBHATA OF TJIE FATtM. ‘JJO Zeilglodon isis, Beadnell, MS. [Text-fig. 78.] 1001. Zoihjlodon C. W. Andrews, Gt'ol. Alag. [5] vol. i. pp. 214-r). J 005. „ ,, 11. J. L. Ecadnell, The To[)()gra])liy and Geology of the F’ayuni Province, p. 44 (Survey D(^[)artinent, Cairo). Type Specimen.- — Right ramus of mandible, complete as far as the hinder end of the molar series (text-Hg. 78) ; Geological Aluseum, Cairo. This is a very large s])ecies, the distance from the anterior end of the mandible to the posterior border of the last molar being about 77 cm. against 48 cm. in Z. osiris. It is distinguished from tlie contemporary Eoccfn,s sclnvei'nfnrtlii in having the molars and premolars serrated. The full dentition is present in the mandible, and the first })remolar is one-rooted. Form. Loc. — Rirket-el-Qurnn beds (Aliddle Eocene): west of Birket-el-Qurnn. The occurrence of large Zenglodonts in beds beneath the Qasr-el-Sagha series, in which the types of Z. osiris were found, was noticed by Dames'* * * § in his account of Schweinfnrth’s first collection, which came from the island Geziret-el-Ciorn in the lake Birket-el-Qurun : the beds in which this collection was made are placed by Beadnell in the Birket-el-Qurun series. The existence of this large species was afterwards referred to by myself f and by Stromer J. Recently, Dr. E. Eraas has described a large Zeuglodont Irom beds of the same age, and has made it the type of a new genus and specii's Eoccftis sch'weinfurfiii stating that in several respects it is more primitive than Zevyiodon and in some respects intermediate between it and Protocetiis. The teeth are described as secodont with a reduced inner tubercle, the edges of the crowns not being serrated as in Zevyiodon ; the full dentition is present in the upper jawe Dr. Eraas also refers to this species the large vertebne from the same horizon. These, however, he admits are closely similar to those of the larger American Zenglodonts. A number of these large vertebrae wmre collected near Dime in 19U0 by Mr. Beadnell and myself, and subsequently he obtained near the western end of Birket-el-Qnrun a fine mandibular ramus of very large size with the teeth of typically Zeuglodont form. I'he dental hninula is : i. 3, c. 1, jwi. 4, m. 3. This animal, from its tooth- structure, cannot be the same as Eocetus sehweinfiirlhi, although of similar size and from about the same horizon. In his notes, Mr. Beadnell referred to this species as * Hit/.ung.sb. 1<. [)reus.s. Akad. Wi.ss. vol. i, (ISSR) pp. lAO-ia.I. t (tool. IMag. [.b] \(;1. i. ])p. 21-t-n. X Itcitr. Fill. u. (teol. Oc.stiMrcicli-Pngarn.s ii. d. Orii'id.s, vol. .\v. (litOA) j). 82. § OrigiiKilly Mesocetus scliireivfnrt/ii ' I’aUcont.. A liliandl., n. s , \'ol. \ i. (li)Od) p. 217), but Jilenocctux baling been previously employed, the author chiinged it to /uiccltis ((uiol. (’entralblatl , vol. v. (lOttl) no. 10-J8). ZEUGLODON ISIS. 241 Zeuglodon isis, a name also employed in his report on the Fayum and adopted here. 'The large vertebra), in the absence of proof to the contrary, will be regarded as belonging to this species. C. 10208. Ivio'lit ramus of mandible, imperfect posteriorly ; the premolars and molars are present, though somewhat broken. Type specimen (text-fig. 78). The total length preserved is about 83 cm. Anteriorly it terminates in a rounded extremity bearing the alveolus of the first incisor ; externally it is convex in front, becoming flatter posteriorly ; internally there is a flat symphysial surface extending back to about the middle of pm. 2. The ramus deepens gradually from before backwards ; opposite i. 2 it is about G'4 cm. deep, while beneath m. 3 the depth is about 22 cm. In the anterior 2G cm. there are the alveoli for four single-rooted teeth : i. 1 is situated at the extreme end ; i. 2 is Text-fig. 78. Eight ramus of mandible and preniolar tooth of Zevglodon isis: A, outer side of mandible, nat. size ; B, inner side of the first premolar, | nat. size. i. 1-3, alveoli of incisors ; c., alveolus of canine ; m. 1-3, molars ; 1-4, premolars. situated about 2 to 3 centimetres behind it, and has an antero-posterior diameter of about 4 cm. ; i. 3 is about .5'5 cm. behind i. 2, and its antero-posterior diameter is about 5 cm.; the canine is about 4‘5 cm. behind the last, and its alveolus is about 5 cm. in diameter. The edges of the alveoli of these anterior teeth are very prominent. The first premolar {jmi. 1, text-fig. 78, A) is in situ; it is a single-rooted tooth with a high compressed crown curving rather backwards ; both its sharp anterior and posterior edges are serrated, the posterior serrations being the coarser (see text- fig. 78, B). The surface of the enamel, especially on the inner side of the crown, is sculptured by a series of fine more or less vertical ridges, which anastomose at intervals and do not run on to the serrations of the posterior border, the surface of which is quite smooth. The height of this tooth is about G’5 cm., its antero-posterior diameter about 5 cm. Pm. 2 is separated from pm. 1 by a space of 5 cm. ; it is a large double-rooted tooth with serrated anterior and posterior edges ; the number of the serrations cannot be made out ; the enamel both on this and the succeeding teeth is sculptured like that of prn. 1. The 242 TERTIAllY VERTEBKATA OF THE FATCtM. next tootli ijim. 3) is separated l)y an interval of about 6 cm, : it is likewise two-rooted, and is niiicli larger than 'pm- 2 ; it can be seen that the posterior border of the crown had a t least three accessory denticles, of which the uppermost is the largest ; the summit of the crown is broken away ; the antero-posterior width is (j'2 cm. The next tooth (/uu. 4) is almost in contact with jmi. 3, to which it is closely similar in form; its antero-posterior diameter is G‘2 cm. Immediately behind ]>m. 4 come three closely crowded molars, which differ from the premolars in having no accessory denticles on the anterior border and only one or two on the posterior. These teeth increase in size from before backwards, the last having an antero-posterior width of 4‘5 cm. ; they are so closely crowded that the hinder border of the penultimate fits into a groove on the front of the last. Beneath the molars the depth of the mandible increases very rapidl}", so that they are arranged in a steeply slojiing line. Mr. Beadnell records the discovery in beds of Birket-el-Qurun age, and associated with remains of Prozeuglodon, of a large nearly complete skull measuring 116 cm. in length. This may belong to either Fraas’s species Kocetus schweinfurtln or to the jiresent form ; but, judging only from a rough photograph by ]\Ir. Beadnell of the occipital surface of this skull, it seems that the former alternative is the more likely, since the breadth of the supraoccipital region a})pears to be greater than in Zevglodon projier. The following specimens are provisionally referred to this species : — C. 10019. A number of posterior lumbar and anterior caudal vertebra} of large size. Of these, two are from the lumbar region (see text-fig. 79) and are closely similar fo those of Z. macro- xjioiidjlus, figured by J. M tiller * on his pi. xv. The ends of the centrum are oval in outline, and in each case the epi])hysis has been lost. The ventral surfiice is convex from side to side, i)articularly near the posterior end; in the middle is a depression into which a pair of vascular foramina open. The transverse processes are fairly large and project forwards and downwards; they are strongly flattened from above dowmwards ; on their upper surface is a ridge which gives them the a}>pearance of consisting of outer and inner elements, thoutih in section this is found not to be the case. Above the base of the transverse processes the side of the centrum is concave. The neural arch, which occnjiies al)out half the total length of the centrum, is situated towards its anterior end ; it is very low, and the floor of the neural canal is concave both from side to side and from before backwards ; at the bottom of the concavity there is a, large vascular foramen. Anteriorly the arch bears a pair of large quadrate metapophysial processc's, but neither the anterior nor the posterior zygapojihyses are devclopeil ; the j)ost(n'ior ]iart of the arch beai’s a low neural spine and is ])roduc(Hl back in the middle line inio a blunt ])oint overhanging the ])0.sterior o|iening of the neural canal. In another specimen, apparently a little iurther back in the s('ri(‘s, there is a deep notch lor tlu' ))assage of a vessel on the anterior border of the ti'ansverse process. Furtlu'r back still In the caudal region this notcdi is converteosterms. Close to the inner angle of this notch tlie body of the bone is l)erroratcd by the condylar foramen, the inner opening of which is on the inner face of the base of the condyle. The su])raoccipital [soc.) forms the whole of the upper part of the occipital surface ; it is gently concave from side to side, and in the middle line bears a vertical ridge which increases in height towards the upper border, but stops short before reaching it. 'fhis bone, together with the parietal, forms the upper part of the extraordinarily developed lambdoidal crest, the two bones sometimes uniting in a suture as much as 5 cm. deep. The lateral portion of the crest for a short distance is formed by the supraoccipital alone, which here extends on the side of the skull, forming part of the posterior end of the temporal fossa?. Beneath this the bone joins the squamosals and by its ventral border the exoccipitals. The hasioccipital {hoc.) is a very broad bone, probably forming the ventral angles of the occipital condyles. Its dorsal (cranial) surface is convex from side to side, the ventral concave. In front near its point of union with the basisphenoid the bone widens out and bears on its outer angles a pair of large roughened tuberosities which project outwards and downwards. The hasisj)henoi(I is a very broad flat bone, uniting with the basioccipital behind in a long straight transverse suture. liaterally the boundaries of the bone are obscure ; probably it imited with the lower end of the alisphenoid, but if so the suture is completely obliterated : behind this it unites in a complicated suture with the squamosal just internal to the inner end of the articular surface for the mandible. In front the bone is overla])ped on either side by the posterior ends of the pterygoid, which runs back to about the level of the glenoid surface. 'Yhe parietals (/)«.) form the roof of the strongly compressed cranial portion of the skull. Posteriorly they unite with the supraoccipital in a very deep suture, forming the upper part of the lambdoidal crest: in the middle line they join one another also in a very deep suture to form the high sagittal crest. The cranial region, though very narrow, is somewhat more inflated than in Z. osiris, and beneath the sagittal crest is gently convex from above downwards. Veutrally these bones unite with the portion of the supraoccipital which ajipears on the hinder wall of the tenijioral fossa, and in front of this with the squamosal in a suture running downwards and forwards ; the antero-ventral angle of the parietals forms a blunt projection apjiarently for musclc- attachnient. The union with the frontals occurs about 3 cm. behind the great supraorbital expansions of those bones ; the suture is a complex one, but, speaking generally, it runs first downwards, then downwards and backwards. In this region both the ])arietals and frontals are enormously thickened. 'I'he frontals {j'r.), as just mentioned, unite in a complex suture with the parietals, PROZEUOLOUON. 247 forming the anterior portion of the narrow skull-roof between the temporal fossae, though the sagittal crest is not actually continued on to them. In front of this they widen out suddenly to form the very broad and massive supraorbital processes, which completely overhang the orbits, the skull-roof at this point being very wide and gently convex from side to side. The posterior border of each supraorbital process is concave and its outer end text-fig. 80) is greatly thickened and turned sharply down at right angles to the roof. In front of the orbit also the frontals are thickened and there join a pair of small bones, the lachrymals {la.), which are wedged in between them and the anterior end of the jugal [ju-). In the middle line in front the combined frontals send forwards a wedge-shaped process between the hinder ends of the nasals; to the side of this they are overlapped, first by the hinder end of the nasals, and external to these by the maxillae, the line of junction running outwards and forwards. The nasals {na.) are of moderate length ; posteriorly, as just mentioned, they are separated for a short distance by the frontals ; in front they meet one another in a median suture. They seem to have been about the same width throughout, but anteriorly they are overlapped to some extent by the facial processes of the premaxillae. Their anterior border in the skull described is incomplete, but it can be seen that they formed the posterior border of the narial opening {nar.), which they overhung to some extent. The rest of the border of the external nares is formed by the large premaxillde [pmx.]. These are greatly enlarged anteriorly, and are strongly convex on their outer face ; the alveolar border bears the three alveoli of the large incisors, the first being at the extreme end of the snout, while the others are separated from it and from one another by intervals of about I '5 cm.: on the outer surface behind and above the second aud third alveoli are slight depressions for the reception of the points of the lower teeth. Within the alveolar border is a rounded ridge, wbich is continued back on the maxilla ; there was a short palatine process. The posterior part of the upper surface of the combined premaxillae is gently concave from side to side, and forms the floor of the narial opening, which is not shar})ly defined in front. Posteriorly the bones send back long facial processes, which are lodged in a groove on the upper anterior borders of the maxilloe and form the lateral borders of the narial opening, deepening considerably posteriorly where they join the nasals ; the facial processes extend back to the level of the interval between the second and third premolars. The maxillw {mx.) are very large bones : by their upper border they unite with the pi'emaxillse in front, receiving the facial processes of those bones in a deep groove along them upper edge; behind this they join the nasals. Their posterior edge overlaps the anterior border of the frontals, to the outer side of which they join first the small lachrymals, then the anterior end of the jugals, beneath which, moreover, they send back a short process which bears the alveoli of the posterior molars. There is a large antorbital foramen {ao.f.) opening on to the side of the face at the level of the 248 TEliTIAKY VEIITEBRATA OF THE FAYtM. anterior root of pm. 3, and beneath it a smaller aperture. The alveolar border is broad : in front are the large single alveoli for the canine, winch is much larger than the incisors, and for tlie first premolar, behind and to the outer side of which are shallow ])its for the points of the lower teeth. Then come the alveoli for the large double-rooted 2 ; behind and to the inner side of the posterior root of this and the remaining ])remolars are deep fossae for the reception of the points of the lower teeth. The third and fourth premolars are large three-rooted teeth which will be described below. The lirst molar is beneath the orbit ; it had two or three roots, there being doidjt as to whether the wide posterior root is merely grooved or actually divided into two. Whether any other molars were present is uncertain, but probably there was at least one more. The palatine surface of the maxilla is raised into a broad ridge as far back as the hinder end of the second premolar; then it flattens out to form the palate and unites behind with the palatines in an oblique suture : there is a pair of small posterior palatine foramina. The inner face of the bone forming the wall of the nasal passage is strongly concave from above downwards : on this face towards the anterior end of the bone is a strong longitudinal ridge increasing in height backwards, perhaps representing the maxillo-turbinal. The lachrymal [la.) is a small element forming a slight projection at the anterior border of the orbit and wedged in between the frontal, the jugal, and the maxilla. The jugal (ju.) is a comparatively stout bar of bone, the anterior end of which is thrust between the lachrymal and the backward prolongation of the maxilla; it forms the ventral border of the orbit. Its free portion is slightly flattened from above downwards in front and from side to side posteriorly ; its pointed posterior end underlies the strong zygomatic process of the squamosal {sq.). This bone is very large and forms the whole of the great lateral expansion of the hinder part of the skull. Posteriorly it unites with the supraoccipital above, then with the exoccipital, and below this again with the mastoid portion of the periotic, l^ixternal to this it forms a broad concave surface, looking backwards and forming the lateral region of the posterior face of the skull. The lambdoidal crest is continued on the squamosal, running downwards in an S-shaped curve, then becoming continuous with the sharp upper border of the zygomatic process. 4'he upper edge of the bone unites with the supraoccipital and in front of this with the parietal, the line of union with which runs downwards and forwards and is raised into a moderately jirominent ridge. Its anterior border is produced forwards as a sharp-edged shelf, the lower face of which is occupied by the glenoid articulation for the mandible. The large zygomatic prominence {zyq.) projects considerably beyond the rest of the bone; })osteriorly it is produced downwards into a large flange-like postglenoid jirocess. The anterior free portion of the zygomatic jirocu'ss is convex externally, its upper edge being continuous jiosteriorly with the lambdoidal crest, as already mentioned ; the jugal runs back beneath it as far as the anterior boundary of the glenoid surhice. riiOZEUGLODON. 240 Internal to the articnlar surface, the squamosal unites in suture witli the alisphenoid, and appears to send down a flange of bone which helped to su])port the great swollen ipnpanic. This element is badly preserved in the available specimens, but it can be seen that it formed a great egg-like expansion with very thick walls and seems to be obscurely divided into a small postero-internal lobe and a very much larger outer one ; it is wedged in between the scjuamosal on the outer side, the basioccipital and (1) the basisphenoid on the inner, and the alisphenoid in front. The periotic {per.), as already described, appears on the posterior surface of the skull between the exoccipital and the squamosal ; on the inner face of the skull it extends some distance upwards. The external auditory meatus opened immediately behind the postglenoid process of the squamosal. The alisphenoid (al.) must have united at its lower end with the basisphenoid, but the suture is obliterated. Immediately in front of the tympanic bulla it is perforated by a large foramen, apparently the foramen ovale'. Above this it joins and is overlapped by the inner end of the portion of the squamosal bearing the articular surface. Above this again it runs obliquely upwards and forwards on the side of the cranium as a wing of bone, which unites behind with the parietal and above with the frontal for a short distance. The upper part of its anterior border forms the outer lip of the posterior end of the deep groove for the optic nerve {opt.), which runs forwards and upw^ards, the upper edge of the groove being apparently formed by the lower border of the frontal and its floor by the orhi to sphenoid {os.). The lower part of the anterior edge of the alisphenoid seems to unite with the posterior edge of the orbital plate of the palatine, which takes a large share in the formation of the side wall of the skull, and along its upper edge overlaps the orbitosphenoid. To the inner side of and slightly below the level of the orbit there is a large orbito-nasal (spheno-palatine) opening (PI. XXL fig. 1 d, o.nf.), which appears to perforate the orbital plate of the palatine and communicates with the nasal passage. The foramina of the skull are not well seen. There is a distinct condylar foramen in the exoccipital. The foramen lacerum posterias probably occupied the interval between the basioccipital and exoccipital and the tympanic. The lower end of the alisphenoid is perforated by a foramen which may be equivalent to the foramen ovale. The foramen lacerum anterius and the optic foramen must have opened behind the edge of the alisphenoid at the bottom of the deep groove which runs forwards to the orbit as above mentioned. The relations of the lower part of the palatines and the pterygoids cannot be made out. From the above description it will be seen that the skull in Vrozeuglodon differs in no important particulars from the skulls of iProtocetus atavus and Zeuglodon osiris, so well described by IJrs. E. Fraas and Stromer respectively. It is, in fact, in some ways intermediate between the turn, as, for instance, in the position of the nares. Th us, if the total length of the skull be taken as 100, then in Protocetus (assuming 2 K 250 TERTfART YERTEERATA OF THE EAYOir. tliat Fraas’s restoration of the snout is correct) the distance of the posterior border of the nares from tlie occipital crest would he represented by 70, in Prozewjlodon by 63, and in Zeu(jlodo)i osir/s hy 51. Other points in which this skull differs from that o{' Protocetiis arc : (1) the rostrum is much broader and more massive, and does not narrow suddenly in front oi pm. 3 ; (2) the nasals are rather shorter and are separated posteriorly by a process of the frontals ; (3) the supiaocci|)ital surface is perhaps a little less concave from side to side. From the skull of ZeiKjlodoii osiris this form is also distinguished by: (1) a relatively rather stouter rostrum and generally more heavily built skull ; (2) the possession of much longer nasals, separated posteriorly by a process of the frontals — this nasal process of the frontals does, however, exist in some species of the genus (see J. Muller, pi. vii. fig. 2); (3) having a very much less concave supraoccipital surface ; (4) the greater inflation of the cranial region of the skull. A plaster cast of the brain-case, taken from an imperfect skull, agrees fairly well, Palatal view of left preinaxilla and maxilla, with piu.'.i and pm. 4, of Pruzcwilodoti airov. (•., alveoln.s of canine; f., fossae for the reception of the jioints of the lower teeth; i. 1-3, alveoli of llu' incisors ; i.r., inner roots of jinn. 3 and 4 ; m. 1, first molar ; 7nx., maxilla ; pm. 1-4, premolars or their alveoli; pmx., premaxilla; s., suture for union with palatine, g uat. size. SO far as it goes, with a natural brain-c.ist described by Dr. Elliot Smith in his ptiper on the “ Brain of the Arclneoceti ” *. In this he states that the natural cast dilfers so far from the artificial cast taken from a skull of Ztiujlodon oatns that it must have helonged to an animal differing gencrically from that form. Upper l)e)itilion (El. XXI. hgs. 1 a, I n ; text-fig. 82). — There are three incisors, which, judging from one of which the crown is well jireserved, were conical sharp- ])ointed teeth directed somewhat forwards. 'I'lie crown is somewhat compre^ssed laterally, and there is a slight keel on the anterior and posterior borders; the eiiaimd at the base of the crown is raised into line ridges. The first incisor is situated at the extreme anterior end of the prernaxllla, the others follow at intervals of about T5 cm. ; * Proc. lloy. Soc. vol. 7J (1003) p. 322. PROZEUGLODON. 251 behind and external to the sockets of i. 2 and i. 3 there are slight pits for the reception of the ti])s of the lower incisors. The canine, represented by its alveolus only, was a very large tooth, much larger than the incisors ; this seems to be a primitive character inherited fiom the Creodont ancestor. The first ])remolar is a single-rooted tooth, separated from the canine by an interval of about 1'5 cm., in which, to the outer side, is a pit for the lower tooth. In the skull described, 1 is just being cut, its point appearing in the middle of the alveolus of the deciduous tooth it is replacing ; this seems to be the first instance in which any indication of a succession of teeth has been observed in the Zeuglodonts. The second premolar is separated from the first by an interval of 1‘5 cm., occupied by a deep pit ; it is a double-rooted tooth with a strongly compressed high cutting-crown ; the anterior edge bears four or five small serrations, while on the hinder edge are two larger accessory denticles and a third smaller one belonging to the cing\ilum. Behind, and to the inner side of the posterior root of this tooth there is a deep fossa for the lower tooth. The third ])remolar is also a large high cutting-tooth, the crown of which is similar to that of pm. 2, except that on its inner side a little behind the middle point there is a prominent enamel-covered buttress, projecting inwards and backwards and supported by a large distinct root ; the presence of a third root in this and the following tooth distinguishes this genus from Zevglodon. In one specimen there is also a small accessory root on the outer side of the tooth between the two main outer roots. The last premolar differs from pm. 3 in having a more molariform crown, the posterior border sloping much less steeply away and the three posterior denticles rising nearly to the same height; on the anterior border the two accessory denticles are larger than on the anterior teeth. This tooth also has a large inner buttress and root. The first molar is considerably smaller than pm. 4 ; there seems to have been only one accessory denticle on its anterior border, while behind the main cusp there are two rising to nearly the same height, so that the edge of the posterior part of the crown is nearly horizontal. This tooth also had a postero-internal buttress, but it is relatively smaller than in the posterior premolars, and it is not clear whether it had a distinct root or is borne on the inner part of the transversely elongated posterior root, imperfectly divided by a vertical groove. If these teeth be compared with those of Protocetiis, they are found to be widely dissimilar. In that genus the dentition, so far as the premolars and molars are concerned, is practically that of a Creodont, the serration of the cutting-edges of these teeth, so characteristic of the later Zeuglodonts, not having been acquired in that early type. At the same time the posterior cheek-teeth [pm. 3-m. 3) possess an inner (third) root and distinct indications of an inner tubercle, both completely wanting in Zenqladon. In ProzengJodon the structure of the posterior premolars {pm. o, pm. 4), and probably also of m. 1, is exactly intermediate, the characteristic serration having been attained while the inner (third) root is not yet lost. The posterior molars seem to be lost, or at least to be undergoing reduction. The large size of the canine compared with the 2x2 TKKTIARY VKRTEBEATA OF THE FATO.M. 252 incisors is us already remarked, a primitive character derived from a Creodont ancestry; in Prozeuglodon the canine seems to have been relatively larger even than in Prvtoccfas. Another Creodont-like character in the upper jaw is the presence witliin the ])osterior upper ])remolars of large fossic for the reception of tin; corn'sponding lower teetli. The pit for the reception of the point of the lower pm. 2 is on tlie alveolar b(n'der immediately behind pm. 1. In front of this the pits are on the outer side of the upper teeth, the upper and lower tooth-series crossing as in ZeiKjlodon osiris (see Stromer, op. cit. p. 07). Mandible (PI. XXI. hg. I e ; text-fig. 80). — The imperfect right ramus of the mandible is preserved, articulated with the type skull. The posterior portions of the coronoid process and of the angular region are broken away, while the horizontal ramus is imperfect anteriorly and has lost most of its ventral border. The condyle is strongly convex from before backwards, the articular surface forming rather more than a (piarter of a circle. From the condyle on the outer face of the jaw a strong shelf-like ridge runs forwards for a short distance, dying away in the strongly convex outer surface of the ventral ])art of the jaw ; when the jaws are closed, the jugal lies in the groove above this projection. The coronoid process is thin and high ; it is' imperfect jmsteriorly, but its anterior convex border is well preserved and in front slopes steeply down to the alveolar border, which, so far as the region occupied by the molars is concerned, is also strongly inclined downwards. The horizontal ramus was comparatively slender, its outer face convex from above downwards, the inner neaily hat; the symphysis extended back to about the hinder border oi pm. 2. Lower Dentition (PI. XXI. hg. Ie ; text-hg. 80). — The anterior ])art of the jaw is incomplete, and its upper border obscured by strongly adherent matrix, so that the alveoli of the incisors, canine, and hrst premolar are absent or covered up. The hrst tooth present seems to be pm. 2. This is a double-rooted tooth with a strongly com- pressed conical crown with sharp cutting-edges, the anterior of which is steeper than the posterior. On the anterior edge there are tliree or four small serrations, while on the posterior there are two accessory denticles of considerable size and a small cusp belonging to the cingulum. The next tooth, presumably -S, is also two-rooted: it is much larger than pm. 2, but tlie crown is imperfectly preserved ; both its anterior and posterior borders were serrated, tlie posterior serrations being few and large, 'fhe next tooth also is badly preserved ; it is smaller than pm. 3, but the ])osterior serrations must have been larger. Behind these premolars are the sockets of two or three molars, the anterior molar being apparently nearly as largo the last ])reniolar. 'I he second molar is just being cut, and there are indications of a third molar behind it. Vertebral Column (text-lig. 83). — 'fhree anterior cervical vertebreC probably associated Avith portions of a skull were collected by Mr. Beadnell. These specimens arc in a remarkably perfect state of preservation, and have almost the ajipcarancc of recent bones. In the atlas (text-fig. 83, A, D) the surfaces for the occi[)ital condyles [cond.) are PROZEUGLODON. 253 ^rcatly eloiig-ated from above downwards, their u])per ends rnnning ont on projecting ])lates of bone, the snmmits of which arc nearly on a level with the upper border of the iienral arch, with the anterior edge of which they are united hy narrow bars of bone, Text-fig. 8;}. Anterior cervical vertebroe of Froze agio don atrox: A, atlas from front ; B, axis from front ; C, third cervical from front ; D, the three anterior cervicals articulated with one another, from left side. at., lateral surface for atlas ; a.z., anterior zygapophvses ; cond., condylar cups of atlas ; ef., epiphysis of centrum; %P., liypapophysis ; n.sp., neiu’al spine ; od., odontoid process ; posterior zygapophyses ; sjnn., passage for first spinal nerve ; t.p., ti-ansverse process ; v.c., vertehrarterial canal. | na,t. size. enclosing a pair of large foramina for the first spinal nerve {sp.n.). The articular surfaces are strongly concave from above downwards and slightly so from side to side. They 254 TEirriAllY YERTEEEATA OF THE EAYtjAf. are separated ventrally hy an interval of about 2 cm. 'J'lie neural arcli is a comparatively narrow bar of bone connected antero-externally with the u})])er border of the condylar promimmees by a thin bar of bone as described above ; on the frotit of the bar there is a low nu'dian rid<>o (vo.syu), but on the hinder face there is a flat ficet, against wdiich the antc'ro-ventral snrface of the arch of the axis tits (see text-fig. 83, D). The transverse process is short and massive and directed a little backw'aids; on the ])osterior lace, immediately outside the edge of the surface for the axis, there is a small foramen, wdiich, how ever, does not seem to perforate the transverse process, but merely leads into the bone. The surfaces for the axis are wide above, narrowing ventrally, and passing into the surface for the odontoid without interruption ; they are slightly convex from side to side. The ventral bar bearing the odontoid facet is stout and is produced dowinvards into a shar[)-hooked hypapophysis [hjjp-] ; from Lucas’s description* it seems that a similar process is present in the atlas oi Zeuglodon cetoides. In the aids (text-fig. 83, B, ])) the odontoid process {od.) is short, blunt, and rounded, passing at least ventrally into the lateral surfaces {at.) for the atlas. These axe (piadrate in outline, and nearly flat or even very slightly concave from side to side. The neural arch is high, and the neural spine (??.«/;.) high and massive ; it is triangular in section, the posterior surface being flat, wdiile the two anterior faces meet in an acute angle, the lower end of which overhangs the odontoid process ; or the ventral face of this projecting jiortion of the arch is a flat facet wliich articnlates with the corre- sponding surface on the posterior side of the neural arch of the atlas (text-fig. 83, D). The posterior zygapophyses {p.z.) are well developed. The transverse })rocess {t.p.) is a flange of bone directed a little backwards, and extending from the base of the neural arch to the ventral border of the centrum ; externally it is divided into an upper and lower process, and its base is ])erforated obli(Hiely by a vertebrarterial canal [v.c.). The posterior face of the centrum is much broader than high ; it is slightly concave, and in this specimen the epiphysis is not completely fused wdth the rest of the centrum. 'Fbe ventral lace cf the centrum is imperfect. The third cervical (text-tig. 83, C, D) is remarkable for the extreme shortness of the centrum, which in the middle is only about 1'5 cm. through, while its width is at least 5 cm. The centrum is oval in outline, and is completed by anterior and posterior epiphyses {ep.), here still separated ; the anterior and ])osterior faces are slightly concave, 'i'lie neural arch is high, and rises into a short stout neural s])ine {n.sp.) directed a little backwards. Both the anterior {a.z.) and ])osterior zygapophyses {p.z.) are well developed and nearly circular in outline, d'ho transverse ])rocess {t.p.) is wide, and consists of a narrower upper bar arising from the base of the arch and a much broader ventral bar from the lower half of the centrum; these unite externally, enclosing a large vertebrarterial canal {v.c.), :ind forming a broad ])latc, the outer angle of which is produced ii little downwards. Aiiu'r. Naliiralisf, vol. (ISO-')) p. TKi. IMiOZKUGLODON ATllOX. 255 The ventral surface of the ceiitnun bears two blunt ridges, se[)arated by a narrow groove. Comparison of these vertebne with those of I'rotocetm atciKm shows that a considerable alteration has taken place, and that there is mncli less similarity to the vertebne of a carnivore. The atlas oi Protocetiis is unknown, but in the axis tbe peg-like odontoid and the relatively long centrum are characters approaching those found in the Carnivora; on the other hand, in Prozeuglodon the odontoid has already become short and blunt, and the centrum is much shortened, as also are the transverse processes ; at the same time, the high massive neural spine is retained. In the third cervical, the great shortening up of the centrum in Prozeuglodon compared with the same vertebra in Profocetus is most striking ; in this case also the transverse processes are reduced, while the neural spine is moderately developed. Comparison with the corresponding vertebrae of Zeiiglodon shows that the present species approaches much more nearly to that genus than to Profocetus. The atlas is similar to the imperfect specimen figured by Muller (pi. xiii. figs. 1,2), except that the ventral bar is not so thick ; in both there is a hypapophysis. The odontoid process is more rounded than in Zeuglodon, its upper surface showing very little trace of flattening, and therefore differing widely from that of Z. zitteli as described by Stromer ; the neural spine overlies the atlas, as described by Lucas. The third vertebra is shortened to about the same degree as in Z. os/ris, and possesses a fairly developed neural spine, said to be absent in the corresponding vertebra in Z. cetoides. This genus in the structure of the skeleton, so far as known, does not throw any new light upon the relationships of the Zeuglodonts to the Creodonts on the one hand or to the Odontoceti on the other; and its chief interest consists in its almost exactly intermediate position between Profocetus and Zeuglodou, both in structure and in time. Prozeuglodon atrox, sp. nov. [Plate XXL ; text-figs. 80-83.] Tgpe Specimen. — A nearly complete skull with right ramus of mandible (described above, and figured on PI. XXI.) ; Geological Museum, Cairo. This is the only species at present known. The length of the skull is GO cm. ; the length of the upper premolar series I8‘2 cm. Form. (& Loc. — Birket-el-Quruu beds (Middle Eocene): a valley about 12 kilometres W.S.W. of the hill called Gar-el-Gehannem (see map in Introduction). C. 9319. Skull with right ramus of mandible. The palatal region and base of the skull aia' imperfect, fn the up[)er jaw the incisors and canine are represented by their alveoli only ; the first premolar is just appearing, while the second, third, and fourth have high secant crowns, the two latter possessing three roots. Oidy one molar is In siiit, and it is TEIJTIAKT YERTEBEATA OF THE FAYOM. 2.-3G iiiicci faiii wlioflier lliis luul two or tliree root?. In tlio mandible the only teeth preserved are llio ihn'e posterior ]»reinolars. Fianred FI. XXL In the following table the dimensions (in centimetres) of this sknll are placed in the first column, the corresponding measnrennmts in l^rofocd us afurus according to E. Fraas, and in .Zeu(/lod(>n osh'is according to Stromer, being given in the second and third columns respectively : — Length from the end of the snout to tlie occipital crest „ ,, ,, ,, foramen magnum ,, from binder border of the narial opening to the occipital crest „ oi' the nai'ial o})ening Bread! li of the narial opening Length from the ])osteriur border of the frontals to the occipital crest Width of the skull at the narial opening ,, at the supraorbital expansion ,, ,, between the temporal fossje „ ,, at the zygomatic process 34 ajip. Jleiglitof occi])ital surface above the upper edge of theforamen magnum. Width between outer ends of condyles 11 app. ,, of foramen magnum Length of premaxilla 31) ., nasals (Ireatest breadth of nasals taken together Distance between jugal and postorbital process of frontal The dimensions (in centimetres) of the n])per teeth (or, where absent, alveoli) : — 'I'ozciKjlodon Proioceius Zenffloflon atrox. ataviis. oniris. (10 GO 70 app. til app. 58 G8 31) 43 3() 7 app. 7 3-8 2-5 1 iro app. 20-5 9-4 4-3 34-5 lG-7 24 (?) 4'5 3-3 34 a])p. 34 38 (?) 11-8 8 13 (?) 11 app. 5 a[)p. 2-G 39 30 34-5 ir)-3 18-5 IG 4o 3-5 4-4 3-5 1 (or, where absent. of their i. 1 (at alveolus) .... b 3 „ '•3 ,, c. ,, 1 ju». 3 jiiji. JUU. 4 ?//. 1 J.erigth of incisor series 9 cm. Length. Width. 1-8 1-3 2-3 1-4 1-9 1-3 3-7 1’8 app 9 9 4-7 1-3 4-5 1-S O' / 1-7 1-8 Length of [U'emolar series IS‘3 cm. K. 9266. Portions of a much biad^en sknll, including flic posterior (cranial) rc'gion, the Irontal expansion, the maxilla, and the jiremaxilla ; the last contains no teeth, but in tlu^ maxilla you. 3, ]un. I, and part of di. 1 are still in situ, and show the three roots of the (iremolars (text-fig. 82). The cranial la'gion is inteix'sting, because nearly all tlu^ sutures remain open, and the structure of the occipital region is w('ll shown (text-lig. 81 ). From this specimen a brain-cast similar to the natural brain-cast d('scrib('d by Dr. I'llliot Smith* has been made (]\1. 92(15). I he dinumsions (in centimetres) ol this speeinien are : — Proc. Roy. Soc. vol. 71 (19U3) p. 323. PROZEUGLODON ATKOX. 257 Widtli of siipraoccipital surface 13'2 ileiglit of siipraoccipital surface above foramen 11‘7 \V'icltli of skull at zygomatic process 15-1 app. „ between outer ends of exoccipitals 22 „ of foramen magnum G app. „ between ends of supraorbital processes 13 „ at temporal fossae 4‘5 Length of alveolar border of premaxilla IIA The dimensions (in centimetres) of the teetli (or their alveoli) are : — i. 1 (alveolus only) i. 3 „ c. 2mi. 1 jwi. 2 ... . pm. 3 ... . pjin. 4 .... Length. Width. 2-5 1-8 2-7 1-7 2-4 1-G 3T 2-4 3-5 2-2 .5-2 1'8 (anterior root). 4'5 3-1 4-3 2-5 Presented hy the Egyptian Government, 1905. C. 9329, C. 9230, C. 9332. Atlas, axis, and (?) third cervical vertebrae, presumablj associated and perhaps belonging to the same animal as the portions of a skull just noticed. Described and figured above (text-fig. 83). These vertebrae are in a nearly perfect state of jireservation. The epiphyses are not fused with the centrum, though still in situ. The dimensions (in centimetres) of these vertebrae are given below : — Atlas (text-tigs. 83 A, 83 D) : Greatest width at surface for condyles 11'2 „ „ „ axis 10-6 „ „ transverse processes 15'7 „ height 10 Width of neural canal 4'9 Axis (text-tigs. 83 B, 83 D) : Length of centrum including odontoid process o'o Height to top of neural spine 12 Width of posterior face of centrum 5'2 app. ,, at transverse process 11'2 ,, of neural canal 3‘2 Height of neural canal 3 Third cervical (text-figs. 83 C, 83 D) : AVidth of centrum 4-8 Height of centrum 4-2 Thickness of centrum (in middle) I'o „ „ (lower border) 1'8 Height to top of neural spine O’G AVidth at transverse processes 10'.5 Height of neural arch 3'2 AVTdtli of neural arch 3 2 L 258 TEKTiAEY VEHTEBEATA OE THE EAYCtM. Class A V E S. Order RATIT^. Genus EREMOPEZUS, Andrews. [Proc. Zool. Soc. 1904, aoI. i. ]). ICS.] 'I'lie distal end of the tibio-tarsns is compressed from before backwards ; there is a well-marked intercondylar groove ; no bony bridge over the groove for the extensor tendons is present. Eremopezus eoc^nus, Andrews. [Text-fig. 84.] 1904. Ereinnpezii.'f eocceimi^, (J. W. Andrews, Joe. cif. ]>. 1C8, text-fi”'. 1.”). T/jpe specimen. — The distal end of left tibio-tarsns (text-iig. 84) ; British Museum. Type and only known species ; alrout as large as the Bhea. Form, d- Log. — Fluvio-mariue beds (Upper Eocene) : north of Birket-el-Quruu. The only avian remains hitherto collected in the FAyum are the distal end of a left tibio-tarsns and a doubtful phalange of tlie pes of a large Ratite bird. The fragment of the tibio-tarsns consists of the articular end and 4 or 5 centimetres of the shaft, and so far as it goes is in good preservation, only the inner condyle being slightly abraded. The outer condyle, the upper angle of which extends some distance up the antero-external border of the bone, seems to be larger in proportion to the inner than in the other Ratites, with the possible exception of StrutJiio. 'fhe condyles are sejiarated by a well-marked intercondylar groove, thus resembling the tibite of Ca.'^uarius and FJiea rather than those of FFpyornis and Ftrntldo, in which the groove is very shallow. The postcondylar ])rominences are small, being much less ]u-ominent than in Ftrufhio, but are developed to about tlie same degree as in Dromwus. 4'h(' outer’ postcondylar process does not extend so far ujrwards as does the condyle in front, and is separated from this last by a sharp aiigh' of about 90° (see text-fig. 84 B, a.), which forms tlie distal end of the bone posteriorly ; the consequence of this arrangenu'iit is that the articulation looks more foruards than is usually the case, though some EREIMOPEZUS EOC.ENUS. 250 iipproxiniatioii to this condition is seen in Struthio, and still more in Rhea. 'L'he surface between the postcondylar processes is slightly concave, and above passes into the posterior surface of the shaft, which, like the articular end, is strongly compressed from before backwards. The lateral faces of the condyles bear deep pits for the attaclnnent of ligaments (text-fig. 84 B). The posterior face of the shaft passes by a gentle slope into the sharp antero-internal border of the bone, which is continuous with the upper angle of the inner condyle, as in Casuar'nis and iJromwus. The anterior face of the shaft near its inner border is deeply channelled by the groove for the extensor tendons (text-fig. 84 A, e.g.) ; this groove is closed at its lower end by a strong ridge running upwards and outwards towards the lower border and forming a prominent rugose surface above the outer Te.\t-fig. 84. Distal end of left tibio-tarsus of Eremopezus eoccenus (type specimen) : A, from front ; B, from outer side : C, from behind. (From Proc. Zool. Soc.) a., angle between outer condyle and postcondylar surface; e.g., extensor groove ; i.c., inner condyle ; O.C., outer condyle ; t., tubercle marking base of tendinous bridge. § nat. size. condyle. There is no extensor bridge, but a slight ridge along the inner side of the groove marks the insertion of a strong tendinous sling (t.). Compared with the tibio-tarsi of other Ratites this specimen appears to combine the characters of several of them. In the depth of the extensor groove it approximates to Rhea and JEpgornis. The oblique ridge which blocks the lower end of the groove occurs also in Struthio, though in this case the groove itself is much narrower. In A^injonds, on the other hand, the ridge is wanting, and the groove runs nearly down to the condyles. The form of the outer condyle and its relations to the postcondylar process are similar to what is seen in Rhea, and to some extent also in Struthio. ^ There seems to be no doubt that this fragment indicates the existence of a large Ratite bird in the Upper Eocene beds of Egypt, but much more material is necessary before its relationships can be determined satisfactorily. O r 9 ^ ij 2G0 TEHTIAllY VEliTEJ3EATA OF THE FAYXJM. A. 843. I )i.stal end of left tiluo-tiirsus. Type specimen, described and figured in Proc. Zool. JSoc. 11H)4, Yol. i. p[). 1(18-170, text-fig. 15, which is reproduced in text-fig. 84. The dimensions (in centimetres) of this specimen are: — AVidth of distal articular end 4'8 „ of lowest end of shaft (at highest point preserved) . . 3‘5 „ from front to back of the outer condyle 3'5 A. 843 a. Phalange of toe, from the same pit as last specimen. This hone is remarkable for the breadth and depth of its proximal end compared with the distal. The dimensions (in centimetres) of this specimen are : — Length 3'1 AVidth of proximal end ,, distal end 1-2 CROCODrLUS AllTICEPS. 201 Class R E P T I L I A. Order CEOCODILIA. Suborder E TJ S U C II I A. llemains of lleptiles belonging to this group are fairly common both in the Qasr- el-Sagha beds (Middle Eocene) and in the Fluvio-marine beds of the Upper Eocene. From the former horizon remains of Tomistoma africanum and of a short-snouted species of Crocodilus have been obtained, while from the latter a Tomistoma {T. gavialoides), a long-snouted Crocodile [C. articeps) and a short-snouted form [C. megarhinus) have been collected. Scattered scutes, vertebrae, and other bones, sometimes in groups probably belonging to a single individual, are of common occurrence ; but since none of these have been found in association with the skull or mandible, their satisfactory determination is difficult and may be deferred till better material is forthcoming. Family CROCODILIDiE. Genus CROCODILUS^ Laurenti. [Synop. Rept. 1768, j). 53.] Crocodilus articeps, Andrews. [Plate XXII.] 1905. Crocodilus articeps, C. W. Andrews, Geol. Mag. [5] vol. ii. p. 481. Type Specime7i. — Anterior portion of a well-preserved skull (PI. XXII. tigs. 1, 1 A, 1 b) ; Geological Museum, Cairo. This is a long- and narrow-snouted species, the length from the level of the front border of the orbits being about two and a half times the width at the same point. There are five premaxillary and sixteen maxillary teeth. The premaxillary region is scarcely at all expanded. Form. (!c Log. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. The incomplete skull which is taken as the type of this species is the best preserved of the crocodilian skulls collected by Mr. Beadnell from the Upper Eocene beds. 2G2 TERTIARY VERTEBRATA OF THE FAYtlM. Tlic posterior ])ortion behind the middle of the orbits is wanting, hut the remainder is complete and nndistorted, though nearly all the teeth are missing. In the general foim of its head this (,'rocodile must have been very similar to the recent species C. c((faj)Iiy<(cttis and C. intermedins, the snout being long and slender, its length being about times as grear as its width at tlie level of the front of the orbits, as in the species mentioned. The upper surface of the preorbital region is somewhat flattened and is bent sharply downwards at the sides to the alveolar border, at least posteriorly : as a whole, the snout is bent somewhat upwards, so that in profile it is slightly concave above ; it narrows gradually towards its anterior extremity, there being scarcely any expansion of the premaxillary region, the posterior boundary of which is, however, marked by a slight notch behind the fifth tooth, where the maxillo- premaxillary suture passes on to the palate. The facial processes of the premaxillse extend back to the level of the alveolus of the third maxillary tooth, while the palatine processes reach only to the level of the interval between the first and second teeth ; there is a small triangular anterior palatine vacuity. The nasal opening is large and an elongate oval in outline ; the nasals extend into the opening, but the premaxillm seem to have just met one another in its posterior border. The anterior angle of the palatine bones is opposite the eighth maxillary tooth, and the anterior angle of the posterior ])alatine vacuities is opposite the ninth. The sculpture of the facial surface of the bones is much more strongly marked in the neighbourhood of the orbits tban it is further forwards. T’he alveolar border of the jaw is sinuous, the concavities being at the junction of the maxilla and premaxilla and between the seventh and eighth maxillary teeth. The alveoli of the anterior premaxillary teeth are comparatively small and are almost in contact in the middle line. They are separated from the alveoli of the second pair by deep pits for the reception of the anterior mandibular teeth, which perforated the upper surface of the snout. The second pair are small, and they are in close contact with the much larger third pair, behind which there is a notch. The fourth pair are large and are separated hy a pit from the smaller fifth and last ])air of premaxillai y teeth, between the ])reniaxillary and maxillary series there is a notch for the rece])iion of the large mandibular tooth. The first three maxillary teeth are comparatively small and nearly equal in size, and are separated by shallow pits. 'The fourth and fifth are much larger, and the sixth is also large and is separated by a i)it from the much smaller seventh. Behind this there is a deep notch in the side of the jaw. The eighth tooth is small, the ninth and tenth much larger ; then come six other teeth gradually diminishing in size from before l)ackwards. The teeth themselves are nearly all wanting in the present specimen, but in one which is well preserved it can be seen that they had sharp anterior and posterior carina' and that the inner face is flatter than the outer; the enamel is marked with fine parallel grooves. As alreatly mentioned, the general form of this skull resembles that of the skvdls CKOCODII.US AliTJCEPS. 2G3 of C. cafapfn’acfus and C. intermedins and to a less degree of C. americanns •, from tin? two former it is distinguished by the much longer nasals and tlie very sliglit expansion of the premaxillary region. In C. americanns also the premaxillary expansion is greater and the snout is rather less elongated. Of the long-snouted Eocene Crocodilia ])reviously described, the present species seems to approach most nearly to C. ardnini, /igno * * * §, from the Nummulitic beds of Monte Zuello, near Verona ; but it differs from the latter in the smaller expansion of the premaxillary region, the comparative narrowness of the interorbital bar, and the less rounded orbits. Crocodilus spenceri, Bucklandf, which Lydekker J regards as identical witli C. ardnini, differs in much the same way, but the premaxillary region seems to be still more expanded than in the Italian form, and, so far as can be seen, it differs also in having the premaxillo-maxillary suture on the palate almost transverse. Crocodilus holcensis, Sacco from the nearly contemporary Monte Bolca beds, is distinguished from the present species by the fact that the nasals do not extend nearly to the nasal opening and, judging from the figure, by the much wider inter- orbital bar ; this latter character may be partly dependent on the age of the individual. Crocodilus vicentinus, Lioy ||, from the same beds, is a wide-snouted form. Although no mandible has been found in actual association with the skull of this species, specimens showing a form and dentition such as might be expected to belong to it have been collected. The most nearly perfect of these (C. 10065) is figured on PI. XXII. figs. 2,2a; it is almost comj^lete, wanting only the posterior extremity of the left ramus : the teeth are for the most part in an excellent state of preservation. The symphysial region is comparatively long and narrow, though less so than in C. catapliractus, C. intermedius, C. ardnini, and probably also than in C. holcensis ; it reaches back to the level of the sixth tooth, and the splenial does not extend into it. The alveolar border is sinuous, the convex portions bearing the larger teeth, which are the fourth and the tenth and eleventh. The horizontal ramus presents no special peculiarities (see PI. XXII. figs. 2, 2 a). There are fifteen teeth in all ; of these the first is rather large and projects forwards. As already remarked, the fourth and tenth teeth are the largest, the eleventh being a little smaller ; the rest of the teeth are small. As far back as the eleventh all the teeth are sharp with strongly carinated anterior and posterior edges, but behind the eleventh they are blunt and rounded. There are well-marked notches for the reception of the upper teeth behind the second, sixth, and seventh teeth, and shallow pits behind the eleventh and twelfth teeth. * Atti E. Accad. Lincei, Memorie, [3a] yol. y. (1880) p. 65, pis. i., ii. t Geol. and Mineral, ed. 1 (1836) vol. i. p. 251, vol. ii. p. 36, pi. x.w'. fig. 1. X Catal. Eoss. Eept. Brit. Mus. vol. i. 1888, p. 60. § Mem. E. Accad. Sci., Torino, [2] vol. xlv. (1896) p. 77, pi. i. figs. 5 a, 5 b. II Atti Soc. Ital. Sci. Xat. vol. viii. (Milan, 1865) p. 393. 204 TERTIARY VEKTEBRATA OE THE FAYt^M. C. 10036. Aiii(>ri()r portion of skull. Type s])(^cimon, floured on PL XXIT. figs. 1, 1a, 1b. TIk! dimensions (in c('nf iinoircs) of this specinum are : — IXtreine lengtii of specimen so far as preserved 43 Distance from anterior angle of orbit to tip of snout ... 37 Widtli of skidl at tlie level of the anterior angle of the orbits. 14 „ snout at narrowest 4'8 ,, premaxillary expansion 5-5 „ nasal openiTig 2'7 Ijcngth of nasal opening 3'3 Distance from anterior end of palatine fossa to tip of snout . 28'2 R. 3322. Plaster cast of the above specimen. Made in the British Museum. R. 3106. Anterior portion of snout of a larger individual. I’resented hy TP. E. de Wmto7i, Esq., 1903. C. 10065. Nearly complete mandible. Figured on PI. XXII. figs. 2, 2 A. The dimensions (in centi- metres) of this specimen are : — Extreme length Length of symphysis AVidtli of symphysis at widest . . Greatest depth of ramus AVidth of articular surface for quadrate 55'8 10-8 8 app, S R. 3323. Plaster cast of tin* above S{)ecimen. Made in the British Jifuseitm. R 3324. Symjdivsial portion of mandible of a rather large individual. Length of the symphysis 13'4 cm. Presented In/ the Egyptian Government, 1904. R. 3105. tSymphysial region of left ramus of mandible of a large individual. Presented hy IP. E. de Winton, Esq., 1903. Crocodilus megarliinus, Andrews. [Text-fig. 85.] 190.J. Crocodilus megatdtinus, C. AV. Andrews, Geol. Mag. [5] vol. ii. p. 482. Type Specimen. — The anterior portion of a large sknll (figured in text-fig. 86) ; British Museum. In this species the premaxillary region is considerably expanded, though longer in proportion to its width than in C. porosiis \ the facial process of the premaxilla extends back to behind the fourth maxillary tooth. Five premaxillary teeth, behind the last a deep notch for the lower tooth. Form. & Loc. — Flnvio-marine beds (U[)per Eocene) : north of Birket-el-durnn. Itemains of a broad-snouted Crocodile, which attained very large dimensions, are found in the U])per Eocene beds. The most satisfact.), so far as preserved, is strongly convex and somewhat triangular in outline. The ulnar crest {a.) projects further beyond the head than in Psephophorus scaldil or in Sp)hargis. Between the anterior thickening, which terminates on the head, and the posterior border the surface of the shaft is concave Test-fig. 87. Left humerus of Psephoplwrus eocmms, type specimen : dorsal and ventral views, a., ulnar crest ; h., head ; c., radial crest ; d., entocondyle. I nat. size. on the upper and lower faces of the bone, but the ventral concavity is deepest. The part of the bone above the radial process is considerably more elongated in proportion to its width than in Psephoplwrus scald 'd and still more than in Sphargis. The radial prominence is very strongly developed, but it cannot be seen exactly what is the form of its ventral surhice, which, however, is not divided into two or more separate knobs, as in Psephoplwrus, and is continued on the ventral face of the bone obliquely back- wards, so that if the line of its direction were continued it would pass through the end of the ulnar process ; in both Sphargis and Psephoplwrus the ridge is placed more transversely. The dorsal surface of tlie shaft opposite the base of the radial process bears a deep oval pit for the attachment of muscle ; in Sphargis this seems to be represented by several smaller depressions. The dista,l end of the bone is incomplete, but, like the upper end, it seems to have been less expanded than in Sphargis. There is no trace of any ectepicondylar groove or foramen. On the whole, the bone resembles the humerus of Psephoplwrus rather than that of ^ Amer. Journ. Sci. [4] vol. ix. 1900, p. 420. PSEPIIOPIIOIIUS EOCiENUS. — TESTUDO. 277 Sphargis, and is referred to a member of that genus, at least provisionally, until further remains are found. C. 10028. Left liiiinerus. Type specimen described and figured in Geol. Mag. [4] vol. viii. (1901) pp. 440-441, fig. 3. The distal end is imperfect, and the whole bone is somewhat abraded at the angles. The dimensions (in centimetres) are : — Length, so far as preserved 19 Width of head 4 „ at upper end 7‘3 Least width of shaft above radial process 4'4 „ „ below radial process 4’2 R. 3017. Plaster cast of the above specimen. Made in the British Museum. R. 3352. Proximal half of a humerus, much sand-worn. Suborder THECOPHORA. Division A. CRYPTODIRA. Family TESTUDINID^. Genus TESTUDO, Linnaeus. [Syst. Nat. vol. i. (1766) p. 350.] Neural bones usually alternately tetragonal and octagonal, but sometimes hexagonal. Costal bones alternately wider and narrower. Suture between the marginal and costal bones and shields usually coinciding ; supracaudal shield usually single. Plastron extensively united to the carapace by suture, with short axillary and inguinal buttresses which do not reach, or only just touch, the costal bones; entoplastron usually in front of the humero-pectoral suture. One of the most remarkable features of the fauna of the Fluvio-marine beds of the Fayum is the number of giant Land-Tortoises, probably of several species, that must have existed during the period at which they were deposited. A considerable number of shells, some in a perfect condition of preservation, have been collected, mostly by Mr. Beadnell. The greater number of these specimens belong to the species Testudo ammon, already described in brief; other species, less satisfactorily known, will be noticed below. TERTIARY VERTEBRATA OE THE FATDM. Testudo ammon, Andrews. [Plate XXIV. ; text-figs. 88-90.] 'I'esltnlo ammon, C. W. An(l^^ws, A Preliminary Notice of a Land-Tortoise from the Upper Eocene of the Fayum, Egypt (de.scription) : Survey Dept., Cairo (with a Note on the Method emjtloyed in Excavation, Strengtliening, and Transport, l)y II. J. L. Bcadnell). 1901. ,, ,, C. W. Andrews, Ceol. Mag. [5] vol. i. pp. .527-530, pi. xvii. Type Specimen. — A nearly complete, slightly distorted shell, probably of a male (described and figured, loc. cit.', also text-figs. 88, 89); Geological Museum, Cairo. In this species the carapace is highly arched, the areas covered by the costal shields being strongly convex. The antero-lateral and posterior marginals are strongly everted ; there is a small nuchal shield. In the plastron the epiplastra are prolonged forwards in the middle line into an abruptly truncated projection (at least in the males). The posterior end of the plastron is notched in the middle line, and the areas covered by the anal plates are sharply defined by deep grooves and notches. Form. & Loc. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. A considerable number of more or less nearly perfect shells of this species have been collected, but at present little is known about the rest of the skeleton. Some humeri, a part of the femur, and some other scattered remains of a large Chelonian may be referred to it, and a nearly complete pelvis has been found in actual association with the shell : of the skull nothing is known. The carapace is strongly arched in all directions, and, looked at from above (text-fig. 88, A), it is somewhat quadrate in outline, owing to the eversion of the marginals at the postero- and antero-lateral regions. The areas covered by the three middle vertebral shields [v. 2-4) form prominent convex bosses, separated from one another and from the costals by deep grooves. The anterior border of the shell is notched in the middle line and somewhat upturned; there is a small nuchal shield (ww.). 'Fhe area covered by the last vertebral shield is strongly convex, as also is thatco\ered by the single ]>ygal shield {py.). In this latter region the shell forms a strong arched covering for the tail, projecting below the level of the rest of the margin. The form of the bones of the carapace ^vill be best understood from the figures (PI. XXIV. fig. I A; text-fig. 88, A). T’he neural bones {N. 1-7) vary considerably in form ; thus in the specimen figuix'd in text-fig. 88 the first is (piadrate, the second octagonal, the third (juadrate, the fourth and fifth hexagonal, with the shorter of the lateral faces in front, the sixth octagonal, and the seventh quadrate. It appears, however, that in the form of the neural bones a considerable range of variation in different individuals occurs (see PI. XXIV. fig. I a). There are three pygals {Fy. l-o), which, as already mentioned, form a strongly convex protection for the tail. Auieriorly TESTUDO AMMON. 279 Text-fig. 88. Restored shell of Testudo amnion : A, from above ; B, from right side. M. 1-11, marginal bones ; m. 1-11, marginal shields; JY. 1-7, neural bones ; Nu., nuchal bone ; nu,, nuchal shield ; Py. 1-3, pygal bones ; pij., pygal shield ; v. 1-5, vertebral shields. About 1 nat. size. 2S0 TEETIAET VEETEBRATA OF THE FATtlM. jind posteriorly tlic marginals (M. 1-11) arc somewhat everted, but in the region of the junction with the plastron they are vertical. The angles of the bridge between the plastron and the carapace are greatly thickened and form a prominent border, upon which the shell rests. 'fhe plastron (PI. XXIV. fig. 1 b; text-fig. 89) is larger and the openings of the shell Text-fig. 89. aid., abdominal shield; an., anal shield; Ent., eutoplastral hone; Ep.p., epiplastral bone ; /m., femoral shield: g., gular shield; li., humeral sliield ; Eyp., hyoplastral hone; Hyp.pi., hypoplastral hone; ptet., pectoral shield ; Xip., xiphiplastral hone. About t nat. size. are smaller than in most of the recent "iant Land-Tortoises. In some individuals, O including the type, the epijdastral region (Ep.p.) is prolonged forwards to a greater or less extent: as these have a deeply concave plastron, they are probably males. In the specimen figured on PI. XXIV. fig. 1 B, however, this projection is very slight: as the concavity of the plastron in this shell is very slight, it may be regarded as belonging to TESTUUO AMMON". 281 n, female. Anteriorly the epiplastral projection is truncated at right angles to the long axis of the shell, and is slightly notched in the middle line. The posterior angle of the rather large entoplastral is on or a little behind the groove between the humeral {Ji.) and pectoral (iject.) shields. The posterior border of the xiphi})lastral region {Xip.) forms a wide, open, V-shaped notch. The gular shields (y.) are paired, and the pectorals {pect.) are very narrow; the region covered by the short anals {an.) is considerably narrower than the part immediately in front of it, from which it is marked off by a deep groove. In addition to the absence of the prolongation of the epiplastrals and the flatness of the plastron as a whole, the shell figured on PI. XXIV. differs from the type specimen in the following points: — (1) it is much smaller; (2) the areas covered by the vertebral shields are less convex; (3) the caudal region is less convex inferiorly ; (4) the shell, as aAvhole, is relatively rather longer and narrower; (5) the groove between the costal and marginal shields is deeper ; (6) the anterior portion of the plastron, in front of a transverse line passing through the hinder angle of the gular shields, is turned upwards and greatly thickened above so as to form a sort of lip, behind which it thins again abruptly ; (7) the anal region and the posterior notch are narrower. These differences do not seem to be of great importance, and may be partly due to age, partly to sex ; at the same time, although for the present this specimen is referred to T. ammon, the possibility that it may belong to another species must not be lost sight of. It is, perhaps, the most nearly perfect shell of a Lower Tertiary tortoise ever found, being undistorted and unbroken, and looking like a recent specimen ; it, like the type specimen, was collected by Mr. H. J. L. Beadnell. Of the recent gigantic Land-Tortoises T. ammon seems to approach most nearly to the Aldabra and Madagascar forms, having like them a nuchal shield and paired gulars. In the general form of the carapace, especially the convexity of the vertebral shields, it is similar to T. gigantea, Schweigger {T. eJephantina, Gunther), of North Aldabra *, but in that species the anterior and posterior marginals are smaller and less everted, and the shell is wider behind than in front. In the plastron also some points of similarity exist : in both it is large, the epiplastral region is prolonged forwards and truncated, and the xiphiplastral border forms an open notch ; on the other hand, in the fossil the plastron is relatively larger, the anterior and posterior lobes narrowing very little towards their extremities. Numerous Land-Tortoises of large size are known from various horizons in the Tertiary beds of Europe and India. T. gigas, Bravardf, from the Upper Oligocene * Giinther, The Gigantic Land-Tortoises (Living and Extinct) in the Collection of the British Museum, pis. iii. & iv. fig. A ; also Proc. Linn. Soc. 1898, p. 14. t Bravard, Considerations sur la distribution des Mammiferes terrestres fossiles dans le Departement du Puy-de-Dome, p. 15 (Clermont-Ferrand, 1844); also Gervais, Zoologie et Paleoutologie franc^aises, ed. 2 (1859) p. 436, pi. liv. 2o 282 TERTIARY VERTE15RATA OE THE EATlJM. of Bournonclc-St.-rierro (Allier), differs from the present species in the form of the plastron, the anterior lobe of which narrows gradually forwards to a point; it also differs in the grc'at convexity of the carapace, the other characters of which unfortunately have not been described. Another Tertiary giant Tortoise, with which T. ammon may be compared, is T. j)crj)in?(ina, described by Deperet and Donnezan^ from the Lower Pliocene of Uonssillon. This species also attained a very large size, one shell measuring 120 cm. in length. The chief points in which it differs from T. ammon are: — (1) the caraj)acc is much less convex and is smooth; (2) there is no nuchal; (3) the ])lastron, ihongh somewhat similar posteriorly, differs anteriorly in narrowing more rapidly and in not having the epiplastral prolongation (which, however, may be a sexual character). T. Icheronis, Deperetf, from the Miocene of Mt. Leberon, is very similar to T. perpiniana, but still larger, the shell attaining a length of 150 cm. It has also more slender epiplastra and xiphiplastra, and therefore approaches the present species in these points rather more nearly than does T. perpimana. The gigantic extinct 'Tortoises of India, such as T. atlas, seem to be closely similar in many ways to these European Tertiary forms, particidarly in the absence in most of them of the nuchal shield — a charactei’ which distinguishes them from the present species. When the original description of this species was written the presence of a nuchal shield had not been recognised, and consequently it was considered that it was more nearly related to the European and Indian Tertiary forms than now appears to be the case. So far as the evidence goes now, it seems that the nearest relationship is with the Aldabra and Mascarene types and perhaps with some of tlie Indian forms, in which a nuchal is also present. Several more or less nearly complete humeri of Land-Tortoises have been found in the same beds as the shells, and though none of them are large enongh to have belonged to an animal of the size of the type specimens of T. ammon or T. headnelli, nevertheless they may be regarded as probably referable to small specimens of one of these species or of T. isis. The shaft forms a strong sigmoid curve. The ulnar and radial crests are both strongly devedoped and make a very acute angle Avith one another ; they are separated by a deep fossa : the ulnar crest rises consideral)ly above the head, Avhich is an elongated oval in form. The dorsal surface of the upj)er part of the shaft is marked by a strong ridge Avith a deep groove on its iniu'r side for the insertion of muscles. The middle of the shaft is comparatively slender and is triangular in section. 'I'hc distal expansion is not so great as in most of the large Land-Tortoises, e. g. T. (ji/ W, E. de Winton, Esq., 1903. R. 3273. Nearly comj)lete and slightly distorted carapace and plastron. The dimensions of this specimen are given below. Presented hij the J^hjuptian Government, 1904. C. 9240. domplete and undistorted carapace and plastron of a smaller individual, probably a female. Figured on PI. XXIV. The dimensions of this specimen are given below. The dimensions (in centimetres) of the above shells are : — C. 813U. (4ypo.) C. 8772. R. 3097. E. 3273. C. 9240. Length of carapace in middle line .... . . 87 88 80 49-7 Greatest width of carapace 65-7 (?) 53 03 34-5 ., height of shell . . 44-7 45*5 47'5 40 + 29-2 Length of plastron in middle line .... . . 77-8 80-7 70 75-5 45-2 „ „ to end of xiphiplastra . . . 85 85‘5 78‘5 80 48-4 Width of anterior lobe of plastron .... . . 32 43-7 33-5 30-5 21 „ posterior lobe of plastron .... . . 34 42 36 37 22-5 Length of bridge . . 38-8 35-5 40(?) 32 app. 22 R. 3099. Portion of left xiphiplastral hone, showing form of anal shield. Presented hy TP. E. de Winton, Esq., 1903. The following humeri may belong to this or one of the other species of the genus described below. R. 3351. Nearly complete left humerus, described above. The dimensions (in centimetres) of this bone are : — Length 18‘G "Width of upper end 5 app. „ middle of shaft 2 „ distal expansion 5‘3 „ „ articulation 4-2 C. 9008. Pistal half of a much larger right humerus, differing from last in being relatively much wider and at the same time more compressed from above downwards. The dimensions (in centimetres) are : — "Width of middle of shaft 2*7 „ distal expansion 7‘8 „ „ articulation (S'3 R. 3098. Proximal end of a right humerus, similar to It. 3351, but rather larger. J’resenled hy IP. 7f. de W'hdon, Esq., 1903. R. 3098a. Uight humerus, wanting radial side of distal end. Length 18 cm.; width of middle of shaft 2 cm. TESTUDO BEADNELLI. 285 Testudo beadnelli, sp. nov. [Text-fig. 91.] Type Specimen. — A shell of which the carapace is somewhat incomplete, but the plastron is in excellent preservation (text-fig. 91); Geological Museum, Cairo. The shell upon which this species is founded is the only one of this form that has been found. It differs so considerably from all the shells of T. ammon that its separation from that species seems fully justified. The chief of these differences Text-fig. 91. Plastron of Testudo headnelli. aid., abdominal shield ; an., anal shield ; Ent., entoplastral bone ; Ep.'p., epiplastral bone ; fem., femoral shield; g., gidar shield; h., humeral shield; Hy.p., hyoplastral bone; Hyp.p., hypoplastral bone; pect., pectoral shield ; Xi.p., xiphiplastral bone. About 1 nat. size. are : — (1 The areas covered by the vertebral shields are very slightly swollen and are scarcely at all marked off by any depression from the costals ; (2) the carapace, as a whole, is less widened out and turned up in front, and it is considerably lower in proportion to its width ; (3) the pygal region is less convex and does not extend so much below the rest of the margin. Otherwise in the arrangement of the bones and shields the two species are similar ; the nuchal shield is well marked. 280 TEETIAEY VEETEBEATA OF THE EAY^M. In the plastron the difFercnces between the two species are considerable. Thus in the present species the length of the bridge is about half the length of the plastron in tlie middle line, in T. ammou it is usually less. In consequence of this the anterior and jiosterior lobes of the plastron, particularly the former, are relatively .shorter. The median portions of the epiplastrals are produced forwards into a ])ointed anterior projection ; in T. ammon, when this projection is present at all, it is truncated. The posterior lobe of the plastron narrows more towards its distal end, and the anal region is scarcely at all marked off by the notch or groove which is so strongly defined in T. ammon. Lastly, the groove between the femoral {fern.) and anal {an.) shields slopes more backwards. It may be added that the whole shell appears to have been less solidly built than in T. ammon. This species is named after Mr, H. J L. Beadnell, by whom the type specimen was found. Form. & Log. — Fluvio-marine beds (LTpper Eocene) : north of Birket-el-Qurun. C. 8773. Shell of which the carapace is somewhat imperfect. Type specimen described and figured above. The dimensions (in centimetres) of this specimen are : — Length of carapace in middle line 75‘1 ,, plastron in middle line GO-4 ,, „ to end of xiphiplastra 71-G AVddth of anterior lobe 33 app. Length of anterior lobe IS app. AVidth of posterior lobe 32-5 Length of posterior lobe 21 app. „ bridge '. 33 Height of shell 35 app. Testiido isisj sp. nov. Tyjje Specimen. — An imperfect shell, wanting the posterior marginals ; Geological Museum, Cairo. This species is founded on a comparatively small rounded shell in which the growth- lines of the bones are strongly marked, forming in places {c. g. on the costals) ])rominent ridges. The areas covered by the vertebral shields are not inflated and ])ass smoothly into the costal region. The neural bones are all hexagonal, with the antero-lateral sides the shortest. There is a very narrow nuchal shield. The anterior end of the plastron is rounded and upturned, but is not greatly thickened as is the case in the carapace of the female of T. ammon (see Plate XXIV.). 'J'he posterior end of the plastron forms a wide open notch ; the areas covered by the anals are sharply separated from the region in front. The presence of the strongly marked growth-lines probably indicates that this is a young animal, but the fiict that all the neurals arc hexagonal seems to exclude TESTUDO ISIS.— TIIALASSOCJIELTS LIBYOA. 287 the possibility of this being tlie young of T. ammon, and even makes it somewhat doubtful whether it should he referred to the genus Testudo at all. For the present, until further material is available, this species may be called T. isis. Form. & Log. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. C. 8774. Shell, wanting posterior marginals, but otherwise nearly complete and undistorted. The dimensions (in centimetres) are : — Length in middle line o£ carapace 38 app. Extreme width of shell 27 Length of plastron in middle line 35 ,, „ to end of xiphiplastra 37'4 Length of bridge 18 Height of shell 21‘4 Family CHELONID^. Genus THALASSOCHELYS, Fitzinger. [Ann. Wien. Mus. i. (1835) p. 121.] Represented only by imperfect skulls, probably of a single species. Thalassochelys libyca, Andrews. [Plate XXV. fig. 4.] 1901. Thalassochelys lihyca, C. W. Andrews, Geol. Mag. [4] vol. viii. p. 441. Tij'pe Specimen. — The posterior portion of an uncrushed skull (described loc. ext. ; figured PI. XXV. fig. 4) ; Geological Museum, Cairo. Known only from imperfect skulls, the characters of which are described below. Form. ^ Loc. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. The specimens of nearly complete skulls of this Chelonian are so much crushed and distorted that they give a very erroneous idea of the general form, and, moreover, they are so much coated with gypsum that the sutures are invisible. For these reasons an imperfect but uncrushed skull has been taken as the type specimen. In this the whole of the anterior portion in front of the epipterygoid {cohmiella cranii) is broken away, but the posterior part is undistorted and in a fair state of preservation. In this skull the temporal fossae are completely roofed in, the squamosal apparently meeting the parietal as in the Chelonidae and Sphargidae ; but from the latter group 1^88 TEKTIAET VEETEBEATA OE THE FAYtM. it is at once distinguished by tlic circumstance that the o])isthotic and the squamosal join as usual, and there is a distinct epipterygoid, indicating that this Turtle is a member of the Chelonidrc. The occipital condyle is trilobate and the basioccipital portion thrusts itself between the exoccipital lobes, reaching the foramen magnum. In front of the occipital condyle the ventral face of the basioccipital is compara- tively hat, and there is no deep depression at its union with the basispheiioid as in Chelone; laterally, together with the exoccipitals, the basioccipital forms a flat vertical surface, which is larger than is found in either Chelone or Thalassochelys. The opisthotics (o.o.) are arranged as in the recent types and are firmly united at their outer ends with the squamosals [sq.) ; they form the upper border of a large fossa into which several foramina opened. The form of the tympanic cavity {t.o.) is almost as in Chelone \ it seems, however, to be a little more sharply defined in front and a little more elongated in a vertical direction. Tlie pedicle of the (piadrate (jq.) is longer than in the recent forms, so that the articular surface for the mandible is further below the level of the palate. The basispheiioid bears a pair of ridges, which converge forwards meeting in the middle line ; on its u]iper (cranial) surface there is a strong median ridge. The opi])terygoids arise by a narrow base and are less flattened from within outwards than in Chelone or Thalassochelys caretta. There is no doubt that the skull here described is that of a member of the Chelonidit', and since in the form of its basioccipital and basispheiioid it resembles the skull of Thalassochelys rather than that of Chelone, it is referred to that genus ; but further material in better preservation is required before its precise position can be made out. C. 10029. Posterior portion of skull, uncrushed but much covered with a reddish inatri.x: and apparently impregnated with salt. The type described in Geol. Mag. [4] vol. viii. p. 441. Figured PI. XXV. fig. 4. The dimensions (in centimetres) of this specimen are: — lleiglit of skull (from basis])henoid to roof) 7’5 (Greatest width at squamosals 15'4 Width between outer angles of the quadrates ,, of occipital condyle 2‘4 C. 10030. Much cru.shed and weathered skull, inconqdete in front, showing the roofed-in temporal fossm. R. 3192. A similar but rather more imperfect siiecimen. r resented hii the E In tills sjiccies the anterior lobe of the plastron is longer compared with tlie ])osterior lobe than in F. antUpia, and the outline of the shell is more regularly oval than in that species. Its probable identity with P. blancl'etiltorni, Reinach, is referred to below. In P. (vyijittiaca from the Lower Miocene of Mogara, the lobes of the plastron are longer in proportion to their width and the form of the vertebral shields is different. Form. & Log. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurnn. Remains of small Podocnemid tortoises are fairly numerous in the Upper Eocene beds, the anterior part of the plastron, for some reason or other, being most eommonly found. One of these was made the type of the present sjiecies Foilocnemis fajumensis, while others have been described by Reinach under the names P. llanckenhorni and P. hlanckenltorni var. ovata, the chief differences between the two species lying in tlie form of the suture between the epiplastrals and hyoplastrals and of the groove Text-fig. 93. Anterior portion of plastron of Podocnemis fajumensis (type specimen). Ent., eutoplastral bone; Ep., epiplastral bone; <■/., gular shield; lEj-p., byoplastral bone; L/., intergular shield ; Ms.p., mesoplastral bone ; n., humeral shield; p., pectoral shield, -j nat. size. (From the Ann. & Alag. Nat. Hist. [7] vol. xi.) between the humeral and pectoral shields. Several other specimens have been examined, and it is found that a considerable degree of individual variation exists in this respect, so that it is not impossible that the different forms described may be merely variants of one species, although further more satisfactory material will be necessary to settle this point. In the type specimen (text-fig. 93) the anterior border is rounded, with slight notches marking the boundaries of the areas covered by the epi(h'rmal shields. 'I'lie anterior lobe widens gently towards the bridge. The eutoplastral is diamond-shaped, all the sides being nearly straight. The suture between the e[)i- and hyoplastrals runs a little backwards from the outer angle of the eutoplastral, then forwards and outwards jiarallcl with the liumero-])Cctoral groove, which is about I'd cm. iii front of it. The intergular is small, the gulars longer, meeting in the middle line for about 1 cm. The humerals extend back to about the middle of the eutoplastral bone (text-fig. 93). ro DOCNEiAI 1 S FA J UMENSTS. 293 In the type of P. hlancJccnliorni* the entoplastral is more elongated and its postero- lateral borders are convex ; the groove between the humeral and pectoral shields curves backwards and crosses the suture between the epiplastra and hyoplastra, so tliat this form differs from the type of the present species both in the shape of the entoplastral and in the relations of the grooves and sutures. In the type of P. hlancJcenhorni var. ovata"\ the entoplastral is similar to that of P. fajuinensis, while the grooves and sutures are nearly like those of the typical P. hlancJcenhorni. Other specimens of plastra still further bridge the gap between the two species : thus one Text-fig. 94. Carapace and plastron of (?) Fodooiemis fajumensis : A, carapace ; B, plastron. abcl., abdominal shield; an., anal shield; Ent., entoplastral bone; Ep.p., epiplastral bone;/r!)i., femoral shield; g., gular shield; h., humeral shield; ITij.p., hyoplastral bone; Ihjp.p., hypoplastral bone; \.g., iutergular sliield ; Ms.p., mesoplastral bone; A. 2-G, second to sixth neural bones; pect., pectoral shield ; Pg. 1-2, pygal bones ; v. 2-4, second to fourth vertebral shields ; Xi.p., xiphiplastral bone. I uat. size. specimen has an entoplastral very similar to that of P. hlancJcenhorni, while the humero- pectoral grooves, although they curve backwards, do not cross the sutures between the epiplastrals and hyoplastrals. From the above observations it appears that it may be fairly assumed that all the specimens referred to are individual variations of a single species, and that Ileinach’s specific name is synonymous with P. fajumensis. The best specimen of this species is a nearly complete shell preserved in the Geological Museum at Cairo (C. 8790) and figured in text-fig. 94. The carapace is * A. von Eeinach, op. cit. p. 27, pi. ix. figs. 3, 4. ■ t A. von Keinach, oj). cit. pi. ix. figs. 1, 2. 294 TERTIAIIT YERTEBRATA OF THE FAYCM. oval in ontlinc and slightly wider ])ostcriorly than anteriorly ; its convexity is not very great, though tlie crusliing, which has resulted in the breaking away of a part of the anterior border and the dislocation of some of the bones, may be to some extent res])onsible for the flattened form of the shell. 4'here are six neurals (N.), of which the anterior five are hexagonal, with the antero-lateral borders much the shortest; the sixth (-A'". b) is pentagonal, its posterior angle being thrust between the anterior part of the sixtli costals, which behind it meet one another in the middle line, as also do the seventh and eighth costals. The nuchal bone seems to have been wide, but is badly ])reserved. The suprapygal (P^. 1) is triangular, with the postero-lateral angles truncated for union with the last pair of marginals ; the pygal (l*y. 2) is nearly as wide as long. Tlie vertebral shields (i;.) are hexagonal, with the anterior and posterior borders convex forwards. Both in its general form and in its structure the carapace is very similar to that of P. madagascariensis. In outline the anterior part of the plastron (text-fig. 94, B) is like that of the type specimen, but the ento[)lastron is rather longer, the postero-lateral borders being longer than the antero-lateral ones. The sutures between the epiplastrals [Ep.p.) and hyoplastrals [Hyp.) are strongly concave forwards. The posterior ends of the humeral shields {]>.) do not reach so far back as the middle of the entoplastral, and the grooves between tliem and the pectoral shield [pect.) do not curve backwards, and so do not cross the suture between the epiplastrals and hyoplastrals. The small mesoplastra {Msp.) are rouglily hexagonal in form ; the xiphiplastrals {Xi.p.) are incomplete posteriorly, but the hinder border of the plastron was clearly deeply notched. The median sutures between the hyoplastra, the hypoplastra, and the xi])hiplastra with one another are almost equal in length. The dimensions of this shell are given below. C. 10202. Anterior portion of plastron. Type specimen figured and described in Ann. & Nat. Hist. [7] vol. xi. (l‘.)03) ]>. 121, pi. viii. tig. 2 c, the figure being reju'oduced as text-iig. 93. The dimensions (in centimetres) of this specimen are approximately ; — Width of anterior lobe immediately in front of bridge . . . ll'o Length of anterior lobe T’.l „ entoplastron 3'7 C. 8509. Anterior portion of })lastron. In this the humero-pectoral groove does not cross the suture between the ejn- and hyoplastral hones, hut terminates with it on the lateral border. The ento])lastral is long; its postero-lateral sides are convex. The approximate' width in front of the bridge is 12\5 cm., the length of the anterior lobe T'o cm., the length of the entojilastron 4'7 cm. R. 3103. Anterior j)art of ])lastron similar to the type sjiecimcn, except that the suture between the e])i- and hyo])lasti’al hones is more concave forwards and just touches the humero- jx'ctoral groove on the border of the plastron ; the entoplastral is larger and its postero- lateral hoi’d('rs are convex. PODOCNEMIS FA.TUMEXSIS.— STEREOGENYS CROMEKf. 295 C.8790. Nearly coiiipleto shell, descrihoil above and ceiiliinetres) of this specimen are : — Length of carapace in middle line Approximate width of carapace Greatest length of plastron .... Width of anterior lobe of plastron Length of anterior lobe of plastron Whdth of posterior lobe of plastron . Length of posterior lobe of plastroti . „ bridge ignred text-fig. 94. The dimensions (in . ’ 10-7 1A4 14-4 7-4 3-7 app. 7’5 5-7 app. 5-9 R. 3346. Anterior portion of a mandible, })robabIy of this species. This mandible differs from that of P. madagascariensis in having a broader symphysis ; the biting surface is also much broader, and is partially divided into two by a median ridge. Genus STEREOGENYS, Andrews. [Geol. Mag. [4] vol. viii. (1901) p. 442.] This genus is nearly allied to Podocnemis, but is distinguished from it by: (1) the great length and massiveness of the mandibular symphysis ; (2) the posterior position of the internal nares resulting from the approximation of the palatines in the middle line to form a floor to the narial passage ; (3) the large size of the intergular shield, which separates the gular and humerals ; (4) the slight development of the axillary and inguinal buttresses. The fact that the anterior vertebral shield is narrower than the nuchal bone (in S. lihyca) was originally regarded as a generic character, but, as lleinach * has pointed out, it is doubtful whether this character occurs in all the species; the same is the case with the separation of the neural bones from the nuchal in front and the suprapygal behind. Reinach has lately described a species of this genus, S. podocnemioides, from the Middle Eocene of the Fayum, which in several respects, e. g. the relations of the intergular shield to the humerals, is intermediate in structure between the typical members of the genera Podocnemis and Stereogenys. Stereogenys cromeri, Andrews. [Plate XXV. flgs. 1-3 ; text-flgs. 95, 96.] 1901. Stereogenys cromerij C. W. Andrews, Geol. Mag. [4] vol. viii. p. 442, fig. 4. 1903. „ „ C. W. Andrews, Ann. & Mag. Nat. Hist. [7] vol. xi. p. 119, pi. viii. fig. 1. 1903. „ ,, A. von lleinach, Abhandl. Senckenberg. naturf. Gesell. vol. xxix. pt. 1, p. 41. Type Specimen. — A skull and mandible (PI. XXV. figs. 2, 3); Geological Museum, Cairo. * Von Reinach, “ Schildkrdtem’este aus dem agyptischen Tertiar,” Abhandl. yenckenberg. naturf. Gesell. vol. xxix. pt. 1 (19U3) p. 34. 29G TERTIARY YERTEBRATA OF THE FAYt'M. In this species, 'svliicli is tlie type of the geinis, the shell is more depressed, wider and more uniformly oval than in S. llhyca from the Beds above. It also differs in ])ossessing a com])aratively narrow nuchal bone, probably narrower than the anterior vertebral sliield; in the later form the reverse is tlie case. From S. iiodocnemioiden, Itcinach, of the same horizon, this species is distinguished by the fact that the humeral shields are widely separated posteriorly by the intergular instead of terminating at the same point. Form, cf JjOC. — Qasr-el-Saglia beds (Middle Eocene) : north of Eirket-el-Qurun. Text-fig. 05. Palatal view of skull of Stcreoijenys cromeri, restored. hoc., basiocciiiital ; ee.jit., ectopterygoid wing ; f.i.e., fossa into which the internal carotid opens ; f.m., foramen magnum; i.n., internal nares ; rn.r., maxilla; p./., jialatine foramen; parietal; ji]., palatine; premaxilla ; pterygoid ; <7., quadrate ; sue., siipraoecipital ; squamosal. About | nat. size. The skull (PI. XXV. figs. 1-3; tcxt-lig. 95) in its general structure is closely similar to that oi Podocnemis, but is broader and more depressed. The supraocci])ital {soc.) is produced backwards into a large median process, the upper surface of which a])pears ou the roof of the skull between the hinder ends of the jiarietals {pa.). These bones are very large, forming the greater ])art of the skull-roof; laterally they join the (piadrato- jugals andjugals in a straight suture, forming wuth those bones a complete covering for the temporal fossag as in Podocnemis. The frontals (/.) arc comparatively small, and extend forwards to about the middle ])oint of the orbits, -where they join the STEUEOGENTS CllOMERI. 207 prcfroutals {pr.f.) in a transverse suture. The prefrontals form the upper borders of the orbits, and join an u[)ward process of the maxilbe to complete the orbits in front. There were no nasals. Posteriorly the orbits arc to a great extent cut off from the temporal fossa by a wall which, as in Podocnemis, seems to have been constituted by the upturned edges of the palatines meeting processes of the jngal and perhaps also in part by the postfrontal The ])remaxillaD {pmx.) are small; they form the floor of the nasal opening, and appear to a considerable extent on the ])alatc, extending back to form the anterior boundary of the cleft {p-f.) wliich runs back between the maxillm ; within and parallel to their sharp alveolar border there is, on the palate, another slight ridge. The maxillm {mx.) form the greater part of the cutting-edge of the jaw and the anterior part of the palate ; in the middle line they are separated by the narrow cleft above referred to, but their edges converge backwards, while in Podocnemis there is a wide open space between them, increasing in width backwards. The palatines join the maxillae in an oblique suture ; their arrangement differs widely from that seen in Podocnemis. Instead of merely forming the posterior portion of the border of the internal nares, they here send in palatine plates, which seem to have met in the middle line forming a secondary hard palate, as in the mammals, and thus carrying back the opening of the internal nares to a point rather behind the middle of the skull. In the type and some other specimens these jDalatine plates do not actually meet, but are separated by a narrow cleft ; though probably this is due to slight distortion from pressure, since in one specimen at least they actually unite. This formation of a secondary hard palate and the consequent posterior position of the internal nares [i.n.) is correlated with the great width of the symphysis of the mandible : probably both the hard palate and the symphysis were covered with broad horny plates and were employed in crushing hard substances, such as the shells of Crustaceans or Molluscs. The form and relations of the palatines and internal nares in Stereogenys are shown in text-fig. 95. The pterygoids {pt.) join the palatines in an oblique suture and from the posterior ends of the palatine plates of the latter bones ridges run backwards and outwards towards the point of union of the former with the quadrates. The ectopterygoid processes {ec.pt.) are very large and together with the anterior upturned edge of the bones form the outer border of deep grooves (PI. XXV. fig. 1, ^.), which above lead into the orbits, into which they open immediately within the posterior wall above mentioned : the arrangement of these parts is almost exactly as in Podocnemis. Postero-laterally the pterygoid joins the quadrate {([.), immediately internal to which is a large foramen for the internal carotid {f.i.e.). In the middle line the pterygoids are to a considerable extent separated by the backward extension of the palatines, but behind this they meet for a short distance, probably covering the anterior part of the basioccipital. The quadrate {q.) differs from that of Podocnemis in being prolonged downwards, so that the mandibular articulation, which is strongly concave from side to side, is borne on a 2 q 1^98 TEliTlAliY VERTEEKATA OF THE FAYOM. short pedicle and is considerably below the level of the lower border of the com- pletely closed tympanic ring, which is oval in outline. So far as can be determined, the form and relations of the squamosal, quadrato-jugal, and jugal do not differ in any im[)ortant respect from those of the same elements in Fodocnemis, and the same may be said for the bones of the side of the cranium. The large foramen i^plienoidale [f-s.) is shown in PL XXV. fig. 1, opening in front of the epiotic. The sympliysial region of the mandible (PI. XXV. fig. 3, sym.) is very large and massively constructed. In form it is roughly pentagonal, the two anterior sides forming the labial borders, the two laterals being produced upwards into strong pointed coronoid processes [cor.), while the posterior side is slightly concave. This posterior border is greatly thickened and deeply grooved ; in front of it the bone thins gradually towards the labial borders. The lateral edges of the symphysis are also deeply grooved {m.g.), the groove being continued back on to the rami as far as the articulation. The ventral surface of the symphysis is very slightly convex in all directions ; it is separated from the ventral surface of the rami by shallow grooves, and probably was covered by a single large horny plate. The rami are not only deeply grooved on the outer face, as already mentioned, but are also hollowed on the inner side. The articular surface [art.) for the quadrate is large ; it is convex from side to side and slightly concave from before backwards : behind it there is a blunt angular process [ang.), the upper surface of which is concave. The extraordinary massiveness of the sym]diysis and the great development of the processes and grooves for the attachment of the jaw-muscles indicate that the jaws with their horny covering must have formed a very powerful crushing-ap[)aratus. A similar modification is observable in some Cyptodiran tortoises, e. g. Lgtoloma, described and figured by Dollo *. Although in no case have the carapace and plastron been found associated with the skull in such a manner as to leave no doubt that they belong to the same individual, nevertheless the shell now to be described may be regarded with reasonable certainty as belonging to the present species. In the first ])!ace, this form of shell, lik(^ the skull, is the commonest occurring in the Qasr-el-Sagha beds, and in the second place it differs widely from the shell of Podocnemis, the only other rieurodiran genus found at this horizon. The most nearly complete specimen is a somewhat crushed shell (text-fig. 9(>), both carapace and plastron being so coated with gypsum that many of the sutures and most of the grooves between the epidermal plates cannot be seen, 'fhe carapace (text-fig. 9G, A) is depressed, this being in part due to crushing, though it is clear tliat the shell was much wider and less convex than in the next species, S. liht/ca, approaching in this respect X as described by lieinach. The number * Hull. Mus. Roy. Hist. Nat. Bolge, vol. iv. (1880) p. 129. Soo also J.ydeklicr, Froc. Zool, Soc. 1889, p. GO. STEIIEOGENYS CROMElil. 299 of neural bones cannot be determined, but it seems certain that, as in the next species, the neural series is separated both from the nuchal and pygal bones by the junction in the middle line of the anterior and posterior pairs of costals respectively. There are eight pairs of costal bones, but the number of marginals cannot be made out. The nuchal bone is large, but much narrower than in S. lihyca, so that, as lleinach has pointed out, it seems improbable that the anterior vertebral shield was narrower than the nuchal as in that species. Scarcely any trace of the epidermal shields is preserved, but the two middle vertebrals seem to have been large and roughly hexagonal in outline. Text-fig. 9G. '5 nal siye Carapace and plastron of Stereogenys cromeri: A, carapace; B, plastron. Enf., entoplastral bone ; g., gular shield ; Ey.p., hyoplastral bone ; Hyp.p., hypoplastral bone ; ig., inter- gular shield; Msp., mesoplastral bone; n., humeral shield; Am., nuchal bone; p., pectoral shield; Xi.p., xiphiplastral bone. nat. size. (From the Ann. & Mag. IXat. Hist. [7j vol. xi.) The plastron (text-fig. 96, B) is relatively large : the bridge is long, being in the specimen described about 20‘5 cm. in length ; while the length of the anterior free lobe is only 11-5 cm., and that of the posterior lobe about 15 cm. The anterior border is slightly concave in the middle line. The entoplastral [Ent.) is large and rhomboidal, the sides being sometvhat convex. The sutures between the epiplaslrals and hyoplastrals are concave in front and run forwards, terminating on the edge of 2p 2 300 TEllTIAllY VEKTEIEiATA OF THE FAYtJM. tlie ])lastr()n in tlio "roove l)et\vceu the humeral [ii.) and pectoral {p.) shields. In some s])eeimens tin* njjper surface of the epiplastrals is raised into a sort of boss near their ])osterior an^le, and from this a slight ridge is continued backwards to the axillary l)uttress. The suture between the hyo- and hypoplastrals {llyp.p.) crosses th(' middle of the bridge and terminates at the inner angles of the small meso- jilastrals {Ms.p.), which are irregularly hexagonal in outline and are wedged in between the outer ends of the hyo- and hy]a)plastrals and the marginals. The sutures between the hypoplastrals and xiphiplastrals {XLp.) make an angle of about 115° with the middle line, and are slightly convex forwards. The posterior border of the ])lastron seems to have been notched in the middle line as in S. lihyca, but in no specimen is this region well preserved. The arrangement of the horny scutes on the plastron is only known in the case of the anterior region. The intergular [ig.) is very large, its posterior point being about on the middle of the entoplastron. Both the gulais {g.) and humerals (/^.) are very small and widely separated by the intergular. In Stercogenys podocnemiohles, Reinach, the humerals are much larger and their posterior angles coincide with that of the intergular; this condition is transitional to Fodocnemis, in wdiich both the gulars and humerals meet in median suture behind the intergular. C. 10027. Skull and mandible, found actually articulated with each other. The skull is somewhat crushed and is imperfect in the premaxillary region. Many of the sutures are obscured by a coating of gypsum. Ty})e specimen de.scribed and figured in Geol. Mag. [4] vol. viii. (1901) i)[). 442-3, fig. 4 ; also on PI. XXY". figs. 2, 3. The dimensions (in centimetres) of this specimen are : — Skull : Extreme length in middle line „ „ from end of the scpiamosals Greatest width (at tympanic opeuiug) Width between the ends of the ectopterygoid processes . „ „ outer ends of quadrate articulations . . „ of quadrate articulation Distance from internal nares to tip of nose AVidth of palate 90 tO-5 9-8* (io 7'5 1-4 4 o IMandible : Total lengtli Length of syaqiliysis . . AVidth at coronoid process articular surfaces for quadrate . E. 3007. Plaster casts of the above specimens. Made in the Ih-itish Miisemn. This measurement is a little exaggerated, througli the distortion due to crushing. STEliEOGENYS CKOiAIERI. 301 R. 3190. I uipcrfoct skull, wanting roof oC right temporal fossa and with palate much crushed. The dimensions (in centimetres) of this specimen are : — Extreme length in middle line 11 ’4 „ „ from posterior end of squamosals .... 1 1’G Greatest width 11 app. Width between the ends of the ectopterygoid processes ... 7‘0 ,, of palate 4-9 Distance from internal nares to tip of nose 5-8 Least width between the orbits 2 Presented hy the Egyptian Government^ 1904. C. 10031. Nearly complete skull, wanting portions of the covering of the temporal foss;e and the left quadrate. The dimensions (in centimetres) of this specimen are : — Extreme length in middle line 10-4 app. „ „ from posterior ends of squamosals . . . . ll'o Greatest widtli 10‘3 app. Width between ends of ectopterygoid processes 7’2 „ of palate 4'3 Distance from interna] nares to tip of nose 5'7 R 3189. Imperfect skull, wanting the whole of the temporal arches and roof. Figured on IT. XXV. fig. 1. Extreme length in middle line 10 + AVidth of palate 4'2 Distance from internal nares to tip of nose 5-8 Presented hy the Egyptian Government, 1904. R. 3202. Posterior portion of two skulls, probably of young individuals of this species. The only notable difference observable between these and the type skull is, that the-cfuadrate articulation is less markedly jiedunculate. Presented hy IF. E. de Winton, Esq., lt>03. C. 10039. Carapace and plastron, somewhat crushed and much coated with gypsum. This specimen was described and figured in Ann. & Mag. Nat. Hist. [7J vol. xi. (1903) p. 119, pi. viii. fig. 1 (reproduced in text-fig. 9G). The dimensions (in centimetres) of this specimen are : — Carapace : Greatest length 47'5 Length in middle line 45 Greatest width (increased by crushing) 41 Length of nuchal bone 7 app. Width of nuchal bone G'oapp. Plastron : Greatest length 44 Length in middle line 41'G „ of bridge 20-5 ,, of anterior lobe 11‘5 Width of anterior lobe 24 Length of posterior lobe 15 app. AVidtli of posterior lobe 24 TERTIAEY VEETEBEATA OE THE FAYCM. Plastron (coyit.) : Length of cntoplastral bone 8-7 AVidth of entoplastral bone SY Jjengtb in middle line of liyo[)lasf ral 7'0 ,, ,, bypoplastral 11 „ „ xipbiplastral t)'5 Length of intergidar shield 8 R. 3345. Anterior portion of jilustron, sliowing tlie thickenings on the inner face of the epiplastrals. AVidt.h of anterior lohe 22 cm. ; lengtli of ditto in middle line 8'2 cm. ; length of cntoplastral G'8 cm. R. 3200. Anterior portion of plastron : the form of the cntoplastral is rather different from that seen in the other two specimens, being more escntcheon-shaped. AVidth of anterior lobe of ])lastron H) cm. a])}). ; length of ditto in middle line 8 cm.; length of ento- plastral (i cm. ap[). Presented hy TL. E. de Winton, Esq., 1903. R. 3347. Proximal half of a left hnmerns of a medium-sized tortoise, provisionally placed here. This specimen is similar to the hnmerns of Podocneinis, e.xcept that the ulnar crest is less developed and the head less rounded, though this latter character may he due to partial abrasion. Stereogenys libyca, Andrews. [Text-fig. 97.] 1903. Stereogenys Uhyca, C. AY. Andrews, Ann. & Alag. Nat. Hist. [7] vol. xi. pp. 115-119, pi. vii. I'dOo. ,, ,, A. von Peinach, Abhandl. Senckenherg. naturf. Gesell. vol. xxix. jit. 1, p[). 41-15, 111. xii., pi. xiii. tigs. 1, C-9. Type Specimen. — A nearly complete shell (text-fig. 97); British Mnseum. This species is distinguished from S. cromcri by possessing a more convex shell, somewhat expanded posteriorly, and a nuchal bone considerably wider tlian the first vertebral shield. From S. 2>odocnemioides it difi'ers in having the humeral shields widely separated posteriorly by the intergidar. Form. A* Loc. — Fluvio-marine beds (Upper Eocene): north of Birket-el-Qurun. 'I'he specimen (text-fig. 97) upon which this species is founded is a very well- preserved shell, wanting only a jiortion of the left side of both the carapace and plastron ; the pelvic bones were found in situ in the shell. Although cracked in all directions this specimen seems to be (piite undistorted and gives a good idea of the form of the living animal. In its general form the shell is very like that of Fodocnemis madacjascariensis, but rather more convex, particularly in the region covered by the last vertebral shield, where there is a well-marked prominence. The carapace is scjiriewhat expanded posteriorly. 'rinn'c are seven neural bones (text-fig. 97, A), the series being separated from the nuchal in front and from the sii])ra[)}gal behind by ihe union in the middle line of ST E liE( )aEN rs LI B YCA. 30:] the anterior and posterior costals respectively. The distance between the anterior neural and the nuchal is d'G cm., that between the last neural and the snprapygal 1-9 cm. The anterior nenrals are much longer than wide, but the series shortens Text-fig. 97. ^ ig Nu 1 ' I Carapace and plastron of Stereogenys libyca : A, carapace ; B, plastron ; 0, shell from right side. Ent., entoplastral bone ; g., gular shield ; Hy.p., hyoplastral bone ; Ilyp.p., h ypoplastral bone ; ig., inter- gular shield; Ms.p., mesoplastral bone; n., humeral shield; Aa., michal bone ; peel., pectoral shield; Pyg-i pygal bone ; v. 1-5, vertebral shields ; Xi.p , xiphiplastral bone. 1 nat. size. (From the Ann. & Mag. Nat. Hist. [7] vol. xi.) from before backwards, so that the posterior ones are wider than long. 't'hey are hexagonal in outline, with the exception of the first and last, which are pentagonal. TEliTIAlJT VERTEBEATA OF THE FATtM. ?.04 owiii<>- to tlio STi Impression of the anterior and posterior faces respectively; in the anterior nenrals tlic antero-lateral borders arc much shorter than the postcro-lateral ones. 'I'herc anm eijilit pairs of costals : as already mentioned, the first and last pairs meet in the middle line (text-fig. 97, A). The nuchal is large and wider than long; it is wider than the anterior vertebral plate which overlaps it ; the anterior border is emargiiiatc. There are eleven pairs of marginals, of which 4, 5, G, and 7 form the base of the bridge, and 5 and G unite with the mesoplastial [Ms.p.). The anterior free marginals have a I’onnded edge, the posterior ones arc somewhat expanded ami have a sharp edge. The axillary buttress is opposite the fourth marginal, the inguinal opposite tin; seventh : both buttresses are weaker and less developed than in most rienrodirans, tlie inguinal being the stronger of the two. The sn|)rapygal {I’ng.) occupies the summit of the posterior prominence above referred to ; it is roughly triangular in outline with convex sides and is of nearly the same shape as tlie oveilying vertebral shield. The pygal is notched in the middle line by the furrow separating the posterior pair of marginal shields. There are five vertebral shields (y.), the anterior of which is very narrow, being much narrower than the nuclial bone beneath it ; in Felomedusa and I’odocnemis the reverse is the case. The remaining vcrtebrals are roughly hexagonal in form, the antero-lateral borders being slightly shorter than the postero-latcral. The posteiior shield is very convex ; like the underlying suprapygal it is triangular in form, but is much larger (text-fig. 97, A, C). There are four costal shields and twelve marginals: no nuchal shield is present. On the anterior borders of the carapace the extent to which the marginals are exposed is very small, but posteriorly, where the carapace is somewhat expanded, the area is much greater. The relations of the shields to the underlying- bones are shown in the figure. '\'\\e plastron (text-fig. 97, B) is large ; its posterior free portion is wider than the anterior and is more than half as long again. The length of the bridge is about equal to the width of the front lobe, but much greater than its length. The anterior border is gently concave. The upper surface in this region is also gently concave from side to side, the concavity being bounded by thickened ridges borne on the cpiplastrals and anterior part of the hyoplastrals [Jhj.p.). From this ridge the surface slopes gently away to the lateral border of tlie anterior lobe. It a])pcars that the upper surface of the anterior lobe of the plastron was covered for some distance from its border by a scries of cpiplastral shields. The entoplastrou {Ent.) is a small escutchcon-sha])ed element, from the outer angles of which the sutures between the e])i])lastral and hyoplasfral bones run forwards, making an angle of about 45° with the long axis of the shell and terminating on the border of the plastron in the notch marking the end of the groove between the hnmeral and pectoral shields. '1 he suture hetwc'cn the hyo- and hypo])lastra (////./>., Eyp.p.) crosses at the level of the middle of the bridge and terminates externally STEREOGENTS LTBTCA. 305 at the inner angle of the mesoplastra [Ms.p.], which are thus wedged in hetwcen marginals 5 and G and the outer ends of the hyo- and liypoplastra. The mesoplastra are longer than broad ; the tw'o inner borders are strongly convex. The borders of the posterior lobe of the plastron arc evenly curved to the posterior angles, except for a slight notch where the furrow between the femoral and anal shields crosses the edge. The sutures between the hypoplastra and the xiphiplastra {Xi.p.) run parallel with the femoro-anal furrows and about 3 cm. in front of them. There is a deep rounded notch between the posterior ends of the xiphiplastrals. The intergular shield [ig.) is very large and extends back as far as the middle of the entoplastron, separating both the gulars [g.) and the humerals [n.). Both these plates are very small: the pectorals {pect.), on the other hand, are large; the suture between them and the abdominals runs across about 3 or 4 centimetres behind the anterior end of the bridge. The limits of the abdominals, the femorals, and the anals are shown in the figure. The bones constituting the posterior lobe of the carapace have their upper surfaces raised into a ridge about 4*5 cm. from, and parallel wfith, their outer borders ; from this ridge they slope away to the thin edge, the sloping surface being evidently in great part covered by epidermal inguinal shields, which seem to have extended back to the posterior ends of the xiphiplastra. The upper surface of the xiphiplastrals bears the bases of the pubes and ischia, as is usual in the Pleurodira, and when the type specimen was found the whole pelvis was in situ. The bases of the pubes are narrower and directed more forwards than in Podocnemis, and the same is the case to a less degree with the bases of the ischia. The ilium is short and stout ; it does not seem to have been much expanded at its upper end. In the middle of the shaft the bone has a fiat antero-external surface and a rounded postero-internal surface ; it forms the greater part of the acetabulum. The pubis is flattened and united with the xiphiplastron by a long narrow base ; the anterior process is shorter than in Podocnemis. The ischium seems to have been slender, but the greater part is missing. The acetabulum is roughly triangular, one of the rounded angles being borne by each of the bones composing it, the angle on the pubis being the most strongly marked. The ilium forms about two-thirds of the cavity, the ischium constituting rather less than half of the remainder. The ilium of Stereogenys podocnemioides figured by Reinach is very similar. R. 3039. Nearly complete carapace and plastron. Type specimen described and figured in Ann. & Mag. Nat. Hist. [7] vol. xi. pp. 115-119, pi. vii. (reproduced in text-fig. 97). The dimensions (in centimetres) of this specimen are : — Length of carapace in middle line 41-5 Approximate width of shell 32 Length of nuchal bone (in middle line) 5’7 Width of nuchal bone 7’5 TERTIAllT A^EKTEBRATA OF THE FAYEM. :;0G AVKllli of froiil; of first vertebral shield BA (Greatest leiigth of ])lastron 40 Lengtii of plastron in middle line B(j'5 „ anterior lobe 9 AVidth of anterior lobe 17’4 liongtli of bridge 17'7 „ posterior lobe 14 AVidtIi of posterior lobe 20-5 Length of ento])lastral in middle line 0 „ byoplastral in middle line 8'5 „ hypoplastral in middle line 9 j, xipbiplastral in middle line 9 „ intergular shield 0 5 E. 3100. Anterior })ortion of a jdastron. The dimensions (in centimetres) are: — Length of anterior lobe of plastron . AVTdth of anterior lobe of plastron Length of entoplastral „ intergular shield . . . . 9-5 19 / Presented hy TF. 7A de Winton, Esq., 1903. E. 3120. Imperfect anterior lobe of plastron, probably of this species. Presented hy TT\ E. de Wintoyi, Esq., 1903. Order S QUA MAT A. Suborder 0 P II 1 1) I A. Family BOID^F. According to Boulengcr* this family includes snakes in wliicli the maxillary, palatine, and pterygoid bones are movable; transpalatine present; pterygoid extending to (piadrate or mandible; supratemporal present, attached scale-like to cranium, suspending (piadrate ; prefrontal in contact with nasal. Mandible with coronoid bone. Teeth in both jaws. Vestiges of pelvis and hind limbs usually terminating in a claw-like spur visible on each side of the vent. * Catiil. Snakes Brit. Alus. vol. i. (1893) p. 71. GIGA^’TOrillS GAESTINI. 307 Genus GIGANTOPHIS, Andrews. [Geol. Mag. [4] vol. viii. (1901) [). 438.] This genus includes very large snakes, distinguished from the recent Pythons in having vertebric in which the neural spine is less developed and the articular surfaces of the zygosphene and prezygapophyses and of the zygantrum and the postzygapophyses respectively are nearly parallel with one another. Gigailtopllis garstini, Andrews. [Plate XXVI. figs. 1-3.] 1901. Gigantoplds garstini, G. W. Andrews, Geol. Mag. [4] vol. viii. p. 438, fig. 1. Tjjpe Specimen. — A series of about twenty associated vertebrse, with some fragments of ribs (PI. XXVI. fig. 1) ; Geological Museum, Cairo. The type and only known species, distinguished by its large size, it having attained a length of about thirty feet (rather more than 9 metres), if the proportions of the vertebrae compared with the length of the body were as in Python molurus. Form. & Log. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. Pemains of this large Ophidian are very common in the Qasr-el-Sagha beds, occurring usually as isolated and much-weathered vertebree. In the type specimen the vertebrae remain united in groups, one of which is figured on PL XXVI. fig. 1. These vertebrae are closely similar to those of Python, the chief differences being that the neural spine is less developed, being confined to the posterior part of the arch, and that the planes of the articular surfaces of the zygosphene and prezygapophyses and of the zygantrum and postzygapophyses respectively are more nearly parallel with one another. In the procoelous centrum the transverse diameter of the anterior cup is slightly longer than the vertical one; the posterior ball is of corresponding form, and looks a little upwards instead of directly backwards ; on the posterior half of the ventral surface there is a low, blunt, hypapophysial ridge [Ityp.). The neural arch is extremely massive, and on its posterior half it bears a small, stout, neural spine (n.sp.). The anterior zygapophyses {a.z.) form strong prominences, continuous below Avith the transverse processes ; their articular surfaces are roughly triangular in outline, and look rather more inw'ards than in Python, in which they are nearly horizontal. The zygosphene {zs.) is a greatly thickened prominence, the articular facets of which look outw’ards and downw’ards and are nearly parallel with the surfaces of the anterior 2 R 2 TERTIAlir VEETEBRATA OF TILE FAYIjM. 3 OS zygapopliyscs wliicli they face. The posterior zygapophyses {l').z.) are strongly ])roinineiit trihedral ])rocesses, the posterior face of which is nearly vertical, the lower l)ears the oval articular surface, while the upper is continuous with the upper surface of the arch ; tlieir upper angles are continued as ridges to the base of the neural spine ; oil the posterior face there is a shallow pit (/’.). The zygantral facets form the sides of the deep zygantrum [za.) in the posterior end of the arch ; they are oval in outline and inclined to the surfaces of the posterior zygapophyses at a very acute angle. The transverse processes {t.p.) are very short and stout ; at their extremities they bear the vertically elongated rib-facets, which are convex in all directions above, hut concave from above downwards below, as in Python ; their lower angles are on a level with the ventral border of the centrum. The trefoil-shaped neural canal is very small, relatively much smaller than in the recent genus. A rib associated with the type vertebra? shows that, while the articular end is just as in Python., the shaft is more compressed from before backwards. The posterior portion of a left ramus of a mandible (PI. XXVI. fig. 3) of a reptile found close to the type vertebrie may belong to this species. The specimen includes the angular and articular region, in front of which it is broken away. The articular surface {art.) is convex from side to side, and concave from before backwards ; it is wider in front than behind, where it terminates in a point ; its anterior border runs inwards and forwards, so that the whole surface is somewhat oblique, ranch as in Python. The angle [any.) is thick and not very prominent ; it differs from that of the mandible of Python in being less sharply marked off from the region in front, 'fhe inner plate of the jaw, which if complete would run up anteriorly to the coronoid ju'oeess, is broken away, but enough remains to show that probably it was separated from the outer plate by a deep channel as in Python. The apparent sculpturing of the surface of some of the bones (see PI. XXVI. fig. 3 a) appears to be due merely to the etching of the surface by drifting sand. If this mandible did actually belong to Gigaiitophis (jarstini, then, judging from its size compared with any vertebrm found, it would seem that the head in this animal was relatively much larger than in recent snakes ; but more satisfactory material is necessary before any definite conclusion can be arrived at. C. 10022. Associated series of about twenty vertebrre and portions of two ribs. Type specimen, described and figured loc. cit. svpru-, also figured PI. XXVI. fig. 1. The dimensions (in centimetres) of one of these vertebra? are : — Grealest height from top of neural sjnne to end of liypapophysis. 5 app. „ v\i(lth (between ends of transverse processes) . . . b'T AV’idlh between outer angles of posterior zygapopliyses . . . 5‘5 „ ,, upper angles of zygosphene 2'1 ,, of articular cup of centrum 2-3 lleiglit c'f articular cup of centrum Q IG ANTOPIIIS GAESTINI.— PTEIIOSPIIENUS, 309 AVidtli of articular ball of centrum 2'4 Extreme length of centrum 4 AVidth of neural canal 1‘7 Height of rih-facets 1'8 app. The combined length of the four united vertebne figured on IM. XXVI. fig. 1 is about 12'8 cm. R. 3188. Large and nearly complete vertebra, figured PI. XXVI. fig. 2. The dimensions (in centimetres) of this specimen are : — Greatest height from top of neural spine to end of hypapopliysis . 5-7 „ width (between the ends of the transverse processes) . G’3 AVidth between outer angles of posterior zygapophyses . . . 6-3 „ „ upper angles of zygosphene 2-9 „ of articular cup of centrum 2'3 Height of articular cup of centrum 1'9 AVidth of articular ball of centrum 2’3 Extreme length of centrum 4 AVddth of neural canal I’o Height of rib-facets 2'2 C. 10210. A number of similar vertebrae. R. 3010. Three similar vertebrae. Presented by the Egyptian Government, 1903. C. 10023. Posterior portion of left ramus of a mandible, possibly belonging to this species. Figured on PI. XXVI. fig. 3. Family PALiEOPHID.F. Large snakes, probably of marine habits. Vertebrte with tall neural spines ; costal articulation placed low down on the centrum. litemal carina on centrum not unfrequently terminating on anterior and posterior processes. This family is probably nearly related to the Pythonidae. Genus PTEROSPHENUS, Lucas. [Proc. U.S. National Museum, vol. xxi. (1899) p. G37.] 1901. Mceriophis, C. AV. Andrews, Geol. Mag. [4] vol. viii. p. 438. The snakes belonging to this genus are distinguished from other members of the family by the presence on the posterior end of the arch above the zygantrum of a pair of strong pointed processes directed upwards and backwards. On their anterior face 310 ^TJiTIA7^Y VEKTEBIiATA OF THE FATIjM. a, rid^c runs downwards and forwards to the base of the anterior zygapopliyses (see ]’L XXVI. tig. 4-15). These ])rocesses, which may perhaps be described as enormously developed ana]io])]iyses, are present, though of very small size, in some of the vertebrae of Pahrophis. The genus was founded by Lucas for the rece])tion of the species ]*. schncherti, a large snake from the Eocene of Alabama, where it occurs associated with remains of Zeuglodons. In the Eocene of Egypt, also, there is one species, likewise associated with the remains of ZenglodoiK Fterosplienus scliweinfurtlii (Andrews). [hlate XXVI. figs. 4-6.] ]1)()1. Ma’nophis schwchifurtJn, C. AVh Andrews, Geol. Mag. [4] vol. viii. p. 4.38, fig. 2. Tijpe Specimen. — A dorsal vertebra (PI. XXVI. fig. 4) ; Geological Museum, Cairo. This species is distinguished from P. selmcherti by having the posterior face of the neural arch above the zyga}itrum considerably more expanded, so that the free portions of the post('i'o-lateral pi'ocesses aie shorter. Form. cO Iajc. — Qasr-ei-Sagha beds (Middle Eocene): north of Birket-el-Qurun. The vertebrae of this species occur in great numbers scattered along the Middle Eocene escarpment, hut only in very rare cases are even two found united or so situated that they may be reasonably supposed to belong to the same animal. 'I’he prococlous centrum is considerably elongated, and is about as wide as it is higli ; the anterior cup is deep aud nearly circular in outline, except beneath the neural canal, where its border is straight; the j^nsterior convexity is nearly hemi- spherical. On the ventral surface there is a strong median hypapophysial ridge {hyp.), usually produced into two forwardly and downwardly directed processes, one situated close to the anterior end of the centrum, the other near the middle. The transverse processes {t.pi.) are short and situated ventro-laterally on the anterior end of the centrum, below which they project considerably ; their outer ends bear the vertically elongated convex surtaces for the ribs, looking downwards and outwards. Erom the [)osition of the rib-facets it ap]5ears that the body must have been laterally compressed to a considerable degree. ITom the u}iper ends of the transverse processes a ridge runs upwards and forwards to the anterior angles of the prezygapophyses {a.z.), which project considerably in front of the centrum ; their oval articular facets are a little below the level of the floor of the neural canal, and look upwards and a little backwards. The articular surfaces of the zygosphene [zs.) are almost ])arallel with those of the prezygapophyses ; they are borne on the ventral face of two })rominent processes, the upper edges of which unite to foru) the anterior border of tlie neural spine. 'I'he })Ostzygapophyses {p.^-) look downwards and a little forwards, their surfaces being about on a level Avith the top of the centrum. The zygantrum [za.) PTEEOSPJIENUS SClIWElNEUllTIir. 311 is divided into two lateral pocket-like cavities, separated by a considerable interval; tile articular surfaces look upwards and inwards. Above these cavities tlie posterior face of the neural arch is enormously expanded, concave from side to side, and produced upwards and backwards into two long pointed processes {l-p.), from the ends of which a ridge runs downwards and forwards to the base of the anterior zygapophyses ; it is this expansion of the posterior part of the arch and the presence of these remarkable lateral processes that is especially characteristic of the genus, though the beginning of a similar arrangement occurs in the allied and contemporary Falceophis * . As in that genus also the neural spine (n.sj).) is high, strongly compressed laterally, but it seems to slope more backwards in the Egyptian form. Compared with the North- American species, P. schucherfi, described by Lucas f, this form seems to differ only in having the posterior expansion of the neural arch considerably deeper, so that the free part of the lateral processes is shorter. Among the vertebrm collected there is a considerable range of variation in size, but very little in structure, the chief points of difference being in the relative length and width of the neural spine (see PI. XXVI. figs. 5, 6) and the degree of prominence of the lateral processes. In some also the anterior process of the hypapophysis is mnch smaller than the posterior, and may in some cases be entirely wanting. The high neural spine and the downwardly directed articulation for the ribs seem to show that in this snake the body was laterally compressed and more or less ribbon- like, as in some recent aquatic snakes, in which the vertebrae are to some extent similar. The occurrence of the remains in association with remains of Sirenians, Zeuglodons, and Fishes lends further support to the belief that this species was aquatic or semi-aquatic in its habits. C. 10194. Complete vertebra. Type specimen figured in Geol. Mag. [4] vol. viii. 1901, p. 439, fig. 2 ; also on PI. XXVI. figs. 4, 4 a, 4 b. The dimensions (in centimetres) of this specimen are : — Greatest height from top of neural spine to end of hypapopliysis . 8'5 ,, width (between ends of transverse processes) . . . 2-5 Width of articular cup of centrum 1’6 Height of articular cup of centrum 1'4 Widtli of zygosphene 1‘9 Extreme length of centrum 31 Width between the ends of the lateral processes of arch . . 4 app. R. 3358. Similar, though rather smaller, vertebra. C. 10195. Smaller vertebra, with long slender spine and prominent lateral processes ; the anterior end is somewhat abraded. Figured PI. XXVI. fig. 5. Extreme height 6‘5 cm. ; extreme length of centrum 2 cm. app. * Owen, lieptilia of the London Clay, pt. iii. pi. xiii. figs. 5-7. t Proc. U.S. National Museum, vol. xxi. (1899) p. 637, pi. xlv. 312 TERTIAET VERTEBRATA OF THE FATtM. C. 10196. Largo vertebra, with tlie summit of neural spine broken away. This specimen, in which tbe neural spine seems to have been very wide, is figureil on PI. XXVI. fig. 6. The length of the centrum is approximately 3‘3 cm. Width of neural spine at base 2'3 cm. R. 3009. Numerous vertebrae. C. 10025. Numerous vertebrae. R. 3360. Numerous vertebrae. R. 3359. Smaller vertebrae. R. 3361. Smaller vertebrae. R. 3366. Numerous vertebrae. Presented by the Egyptian Government, 1904. Presented by the Egyptian Government, 1904. Presented by Baron JS'opcsa, 1905. FA.] UM r A SCllWEINFURTII I. 3U] Class PISCES. Remains of Fishes are fairly common in the Qasr-el-Sagha beds, but are rare in the Fluvio-marine (Upper Eocene) series above. The commonest forms from the lower horizon are large Siluroids and Sawfishes ; these have been described by Dr. E. Stromer *, so that here it will only be necessary to give a brief account and list of the specimens in London and Cairo. Subclass TELEOSTOMI. Order A C T I N O P T E R Y G 1 1. Suborder 0 8 T Alt 1 0 P II Y S I. Family SILURID.E. Genus FAJUMIA, Stromer. [Neues Jahrb. 1904, vol. i. (Abhandlungen) p. 3.] This genus was established by Stromer for the reception of a species of Siluroid of which remains are very common in the Qasr-el-Sagha beds. It appears to be allied to Arms, one of the chief differences being that the complex vertebra is not fused with the skull, there being no subvertebral process at the iunction. Fajumia schweinfurthi, Stromer. 1904. Fajumia schweinfurthi, Ernst Stromer, Neues Jabib. vol. i. (Abbandlungon) p. 3, pi. i. figs. 1, 2. Type Specimen. — A skull ; Pala3ontological Museum, Munich. In this species the skull-roof is flat except in the supraoccipital region, where * Neues Jahrbueh, 1904, vol. i. p. 1 ; vol. xviii. (1905) pp. 37, 163. also Beitr. Pal. u. Geol. Oesterreicb-Ungarns u. d. Orients, 2 s oil TERTIARY YERTEBJiATA OF THE FAYCJM. it slopes away on eillu'r side' of a incclian ridge. Most of the up])er surface is covered with ])roudiient tubercles, Avhich show a tendency to arrangement in longitudinal rows. 'I'wo douhh' rows of es])ecially large tubercles run on either side of the fontanelle, converging in front (jf and behind it; the o])ening itself is situated towards the front of the skull and at the bottom of an elongated furrow, the sides of which are not tuhercnlate. The snpraocci])ital does not project far behind the rest of the skull and evidently united closely with the large interneural plate. The epiotic processes piojcct strongly backwards and outwards, and bear on their postero-inferior face an elongated surface for union with the post-temporals. The ethmoid is broad, and its anterior border nearly straight, so that the snout appears to be abruptly truncated. 'The anterior complex vertebra is long and biconcave as usual ; its ventral surface is deeply channelled for the dorsal aorta, and, in older specimens at least, the channel IS com[)letely enclosed in its middle region. A pectoral spine, which ])robably belongs to this species, bears a row of transversely elongated tubercles along its convex border and near its extremity; the upper surface also is tuhercnlate. Form, cf- Loc. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. C. 10197. Nearly complete skidl. The dimensions (in c(‘ntimetres) of this specimen are : — Length from basioccipital to tip of snout R2-5 Greatest w idtli at posterior end IG'Tapp. „ ,, anterior end 17'5 C. 10198. Portion of skull-roof, well preserved ])osteriorly and showing the senl[)ture. P.10240. Well-preserved skull, with anterior complex vertebra still united. The dimensions (in centimetres) of this specimen are : — Length from basioccipital to tip of snout 32-4 „ SLipraoccipital to tip of snout 30 Greatest width at posterior end 20 app. „ ,, anterior end fO'4 Length of complex vertebra lO'S Fi'exeiitcd Inj the Eijijptlan Gocernnient, 1301. P.10250. Posterior halt of a skull. The gnaitest width at the posterior end is 1(1 cm. Fee^eiiled /p/ Jhiron dSopesu, PdOo. P.10251. Portions of two similar skulls. I’re.seiiled />// Haeon dSopesa, llKhl. P. 10245. I’ortion of skull, in which the .sculpture of the roollng-hones is well shown. S(K-X()IM':A (iKANDIS. 31“) Ciciius SOCNOP^A, St roiiicr. [Neucs -Talirl). 1004, vol. i. (Al)li;uulliii)o’(>n) O.'] 4’his genus was founded hy Stroiner for tlic reception of a single species of large Siluroid from the Qasr-el-Sagha beds. The basioccij)ital is said to bear paired ])rocesses for union with the post-temporal, as in Bagrus, to which this form is ])robably nearly related. Socnopaea grandis, Stromcr. 1004. Socnopera grandis, Ern-t Stronier, Neue.s Jalirb. vol. i. (Abliandhingen) pp. 6-7, pi. i. fig. 3. Ti/pe Specimen. — An imperfect skull; Palmontological Museum, Munich. 'I'his species seems to have attained a very large size. The sculpturing of the skull- roof differs widely from that of Fajnmia, and consists of numerous small tubercles arranged in longitudinal lines, there being no rows of specially enlarged tubercles at tlie sides of the median depression. This latter is long and sharply defined ; into it there open two fontanelles, one near its anterior eird, the other near the middle. The supraoccipital region projects considerably behind the rest of the skull. Form. & Loc. — Qasr-el-Saglia beds (Middle Eocene) : north of Birket-el-Qurun. C. 10199. Skull and large part of the skeleton of a very large individual. The principal parts preserved are : — (1) Skull, somewhat incomplete towards the outer angles of its anterior end, showing the characteristic scn]})ture ; (2) portions of the mandible and hyomandibnlar ; (3) part of the vertehral column, including the anterior complex vertebra and a series of about nineteen others ; (4) the interneiu-al jdate wdth the dorsal spine ; (5) portions of the two halves of the shoulder-girdle with the pectoral spine. This s])ecimen shows that these Eocene Siluroids attained a large size, the skull being about 65 cm. long, about 21 cm. wide posteriorly, and 32 cm. wide in front; the length from the basioccipital to the tij) of snout is 5(5’5 cm. The complex vertebra is about 15 cm. in length, and the vertical diameter of the anterior end of its centrum about 5*7 cm. The arrow-head-sha])ed interneural plate is large, its length in the mid-dorsal line being 11 cm., length to posterior angles 17 cm., greatest width upwards of 12 cm. Its dorsal surface is covered with an ornamentation of rounded tubercles arranged more or less in lines, and rather larger and more prominent than those on the skull-roof. The posterior notch is occupied by the small su{)porting s[iine of the usual form, and behind this by the large dorsal spine; tliis was probaldy about 20 cm. long and curved backwards ; it seems to have had a tuberculate anterior border and sides marked by fine irregular rirlges. The width of the base of this s])ine from side to side is 4'3 cm., the width of its middle region from before backwards about 2’5 cm. The 2s2 TERTIARY VERTEBRATA OF THE FAYCtM. :;1G ])(‘(;t()r;il spines are still aiiiciilat(Ml with the shoiihler-ginlle ; so far as can be seen the oriiainentatlon was similar to that of the dorsal spine ; the length of these spines must have been about 17 cm., their width at the base 3’5 cm. P. 10258. Ijarge imperfect skull, wanting the posterior portion ; the greatest width of its anterior end is about 23 cm. Presented hy the Eyyptian Gooernment, 1901. The following specimens belong to various Siluroid fishes, but cannot be more definitely determined ; — P. 10252. Anterior complex vertebra of a particularly long and slender form. Its length is IG‘1 cm. ; the depth of the anterior face of the centrum about G cm. Presented hy Baron JPopcsa, 1905. P. 10253. Three anterior complex vertebrae, similar in form but of smaller size than last. Presented hy Duron Nopcsa, 1905. P. 10251. A number of anterior dorsal vertebrae with short disc-like centra. One of these measures 1'7 cm. in length at its ventral edge, while its height and width are about 5'3 cm. Presented hy Baron Eopcsa, 1905. P. 10255. Vertebrae, probably from further back in the column. The centra are much larger than those just described. They are in most cases deeply biconcave, and laterally are excavated by a pair of dorso-lateral depressions and a pair of ventro-lateral depressions. Presented hy Baron Nopcsa, 1905. P.10241. Anterior complex vertebrje and the three succeeding disc-like vertebrje of an individual of large size. The length of the complex vertebra is IGA cm., the height of its anterior face about G cm. Presented hy the Eyypllan Government, 1904. P. 10242. A series of united dorsal vertebrae with very short centra. The processes are well preserved in some part of this column. Presented hy the Eyyptian Government, 1904. P. 10246. Two very large and massively constructed vertebrae. One of these bears w<>ll-develoj)ed zygapophyses, such as may he seen in the vertebral column of Bayrns. The peculiarity of these processes is that the articular surfaces of the anterior zygapophyses look outwards and downwards, those of the posterior, here sessile on the centrum, upwards and a little inwards, the opposite to what usually occurs in the higher AArtebi'ates. C. 10201. Long and slender anterior complex vertebra, similar to P. 10252. Length IG cm. C. 10200. Much smaller and especially shorter complex vertebra. Length 9 cm. C. 10052. Series of six dorsal vertebrcC with disc-like centra. C. 10049. Large, deeply biconcave vertebrcE similar to P. 10255. P. 10257. Imperfect pectoral spine. Tlie anterior edge bears a row of transversely elongated tubercles near the tip ; the sides of the spine also are tuberculate. Length so far as preserved IG'4 cm. PEISTIS FAJUMENSIS. 317 Subclass ELASMOBRANCHIL Order SELACHII. Family PKISTIDiF. Genus PRISTIS, Latham. [Trans, Linn, Soc. vol. ii. 1794, p. 276.] Rostral teeth firmly implanted in sockets, forming square notches on the sides of the saw-like rostrum. Pristis fajumensis, Stromer. 1897. Propristis schweinfurthi, F. Priem, Bull. Soc. Geol, France, [3] vol, xsv. p. 228 [errore). 1905, Pristis fajumensis, Ernst Stromer, Beitr. Pal. u. Geol. Oesterreich-Ungarns u. d. Orients, vol. xviii. p. 49, pi. vi, figs. 1-3. Tjjpe Specimen. — Portions of a rostrum ; Palaeontological Museum, Munich. This species is a true Pristis, the teeth being set in calcified sockets, forming quadrate notches, about 23 in number, on the sides of the rostrum. Form. & hoc. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun, C. 10203. A nearly complete rostrum (text-fig. 98). In this specimen there are 22-23 notches for teeth on either side ; posteriorly these ai’e not opposite one another on the two sides. Text-fig. 98. hut to some extent alternate ; at the extreme anterior end the notches are opposite to one another. The dimensions (in centimetres) of this specimen are : — Extreme length 87 Greatest width of base of rostrum 8-2 Width of tip of rostrum 1'3 Distance between two posterior teeth 4'1 „ ,, anterior teeth 1'5 C. 10204. Portion of a rostrum, with notches for teeth much more closely set than last. Possibly another species. 318 TEHTIAKY YEliTETUJATA OF THE FAYfJM. P.10256. V ortloiis of roslrn, probiibly of tliis species. Presettled JJaron dS^apesa, 1905. P.10243. P roximiil portion of a rostrum. Presented htj the I'djijpi'mn Govertimenl, 190-1. C. 10205. Koslral tootli, proluiOly of tliis species. From the Birket-el (^iirun s(*ries of tlie Zeuoloilon Valley, to tlie south-west of the lake, a cou.'ideralihi numher of laroe rostral teeth were collected by Mr. F)oa(lnell, and are in the Geological Museum, Cairo. These [u’ohahly belong to Stromer’s species Prist is ititjetis {tom. cit. p. 47 j. Cienns PROPRISTIS, Dames, [Sitzungsh. k. preuss. Akad. M iss. Berlin, math.-phys. Cl. 1883, p. 130.] In this genus the alveoli of the rostral teeth are not ossified, and their position is only marked by shallow indentations in the rostral margin. Propristis schweinfurtlii, Dames. 1883. Propristis scJnceiti/nrtlii, Vd . Dames, Joe. cit. vol. i. p, 13(1, pi. iii. figs. 1 a-c, 2. 190.5. „ „ E. Stromer, Beitr. Pal. u. Geol. Gesterreich-Ungarns u. d. Ctiieiits, vol. xviii. p. 53, pi. vi. tigs. 17, 17 a, 17 h. Tupe specimen. — A portion of a rostrum ; Royal Museum of Natural History, Berlin. Remains of this species are not uncommon in the same beds as those from which rostra of Pristis fajttmcnsis are obtained. Form. & Loc. — Qasr-el-Sagha lieds (Middle Eocene): north of Birket-el-Qurun. C. 10206. A ])ortion of a rostrum, closely re.semhling that figured by Stn luer, tom. cit. pi. vi. fig. 1 7. P.10244. A similar portion of a rostrum. Presetited Ip the Ktjt/ptiati Gorertiitietil, P.IU J. Genus EOPRISTIS, Stromer. [Beitr. I’al. u. Geol. Oesterreich-Uugarus u. d. Orieuts, vol. w iii. ( 1!)05) p. 52 (as a suhgenus of /*rislis).] This form seems to be as distinct from I*risfis as is J'ropi istis, :tnd on tlud ticconut it is here regaidcd as of generic rank. In this genus there is no trace of tilvetdi for tlie teeth on the sides of the rostrum. E( )1‘U I STl S KElNACll I AET015ATIS. — CARCli A RODOX. 310 Eopristis reinachi, Stromer. 1005. reinachi, E. Stromorj loc. cit. p. 52, jtl. vi. fig. 15. T>ll)e Specimen. — Portion of a rostrum; PaUcontological Museum, Munich. Form. & Loc. — Qasr-el-Saglia beds (Middle Eocene): north of Birket-el-Qurun. P. 10247. Proximal })ortion of a ro.strum very similar to the type specimen. Family MYLIOBATID^. Genus AETOBATIS, Muller & Henle. P. 10249. Lower tooth-plate of a species of this genus ; similar to that tignred by Siromer (Eeitr. Pal. u. Geol. Oesterreich-Ungarns u. d. Orients, vol.xviii. pi. v. fig. H). Eluvio-niarine beds (Upper Eocene) : north of Birket-el-Qurun. Family LAMNID.E. Genus CARCHARODON, Miiller Ilenle. P. 10248. Tooth of a species of this genus. (?) Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. ■' :^-l ' fcf, .1 1 i '9 INDEX [The asterisk indicates tliat a figure is given on that page.] ACTIXOPTERYGir, 313. Ae/ohatis, 319. Ancodon, 178. [forringei, 179. astragalus, 1 88 *. os innominatum, 185*. parvus, 189. mandible, 190*. sp., 191. AntheacotiieriidjE, 178. Apterodon, 225. macrognatlius, 22G. mandible, 226 *, 228 *. humerus, 229 *. tibia, 230 *. astragalus, 231 *. Arch.eoceti, 234. Arsinoitheriid.®, 2. Arsinoitherium, 2. skull, 2, 3*, 8*, 11*, 13*. brain, 15, 16*. dentition, 17, 18 *, 21 *. atlas, 24, 25 *. axis, 26*. vertebral column, 27, 28-31 *. sternum, 32. scapula, 32, 33*. humerus, 34, 35 *. radius, 36*. , ulna, 37, 38 *. manus, 40 *-46 *. pelvis, 47, 48 *, 61 *. Arsinoitherium (cont.). femur, 49, 50 *, 61 *. tibia, 52 *, 61 *. fibula, 53 *, 61 *. patella, 51 *. pes, 54, 55 *, 61 *. skeleton, 60 *. andrewsi, 81. dentition, 18 *. humerus, 81 *. zitteli, 2. skull, 3*, 8 *, 11*, 13*. brain, 16 *. dentition, 21*. atlas, 25 *. axis, 26 *. vertebral column, 28 *-31 *. scapula, 33*. humerus, 35 *. radius, 36 *. ulna, 38*. forearm and manus, 40 *. scaphoid, 41 *. lunar, 42 *. cuneiform and pisiform, 44 *. magnum, 45 *. unciform, 46 *. metacarpal, 47*. pelvis, 48 *. femur, 50 *. patella, 51 *. tibia, 52*. 2 T INDEX. ArshwUhcrium zitteli (coiit.). ill)ul:i, 5:5*. (■iilciiiieuiii and astragalus, i)a\ icular, -57 *. cuboid, 5S iiudalarsals, 5!) *. vsludeton, GO *. jxilvis and hind limbs, Gl*. A IITIODACTYLA, 178. A V ns, -58. J5aiiypoj)a, 1. systematic ijosition, G2. IbvnVTHEIillDAi, 172. Ilanjlherhim, 172. skull, 172. dentition, 172. inaudible, 173. tore limb, 17-1. bind limb, 17G. (jntve, 17G. Vanharodoil, 310. ( 'akniyoka, 218. t'lCTACEA, l'3-l. ClIELONIA, 275. < 'iiELuxinAJ, 287. t’liOCODlLlA, 2G1. I 'roioddvs articeps, 261 . megarliimis, 2G4. snout, 2G5*. sp.. 2GG. ( 'iiYPToniiiA, 277. E I. V s -MOP. It A>' cii 1 1 , 3 1 7 . Iristig, 3 1 8. • reinaclu, 310. Fjiiaircn, 107. Idji/ca, 108. skull, 108, 200*. brain, 202 *. maxilla, littk in: indible, 20t). \ omer, 20 1 . dentition, 203). vertcbnd column, 213. os innominat um, 2 1 I *. Eotherium, 197, 204. ^’^yptiacum, 204. skull, 205*. mandible, 211 *. os innominatum, 110, 214* Eremopezus, 258. eocamns, 258. tibio-tarsus, 250 *. Euspciiia, 2G1. Eajumia, 313. scJnveinfurthi, 313. Geniohyus, 103. fajumensis, 105. major, lOG. preniolars, lOG*. — — — minis, lt)3. Giyantophis, 307. yarsiini, 307. Halicorid.e, 107. Hulitlurimn, 109, 201, 213-215. os innominatum, 214*. Hycenodon, 218. Hy^xodontid.-e, 218. IIyracoidea, 83. LAMNIDyR, 310. Mastodon americanns, 107. brain, 107*. Meyalohyrit.r, 87, 02. eoca’ints, 02. dentition, 02, skull, 03, 05 *. Moeriophis, 300. MtEtiPPllERIIUyE, 00. Mairithcriam, 00. skull, 00, 100*. brain, 105, lOG *. dentition, 1 Ot!, 1 (.)!), 1 1 1 *. Yertebnd column, 1] maSni()j>it, 28l?. i'lhlo/>iirt, 288. tSlIlKMA, 1!)7. fSooMjxra, 817). 818. Sl’HAIldlD.K, 27.'). i^lrreoi/t’iii/s, 29.'). n-omeri, 29.'). shell, 299 *. skull, 29(1*. lihiica, 802. shell, 808 *. pofloc)iem{o'i(I('s, 800. SUIDTE, 198. TlOLEOSTOill, 818. Tustudinid.®, 277. 'J'estudo, 277. Teslinlo fiiiniiou, 278. shell, 279 *, 280 pelvis, 288*. hcKifnelJi, 28.8. plastron, 28.8 *. isis, 286. 'I'halnKsorhdi/s, 287. lifnpa, 287. Thecopuoka, 277. T()ijilsto'in((, 267. (tfricanum, 270. snout, 271 *. (javialoide.s, 267. ler-iniense, 274. Zei‘(jlodon, 236. i.sis, 240. mandible, 241 *. vertebra, 248 *. osiris, 286. mandible, 238 *. ZEUGJ.onoNTLDii;, 234. riilNTI.i) JiY TAYEdU A.NJ) V'H.VKt'lS. Kl'l) MON COURT, I'MCET STREET. " < .. ,, ’. ■ >' ■' .:. * a •J > ' «-• ?, _ i I "'e' 'y » 4 t, .4 ..'•I' ‘ .. " ;■ I - ■. ■ ';U * ■ 'I' ^ '■• ^ », •( I I ..i » I';- •' I a i ri.ATE I. Fig. Page 1. Avsinoitheyium zitfeli, Beacliiell; skull, left lateral view; the ends of the horns have been restored : one-third nat. size. Flnvio-marine beds (Upper Eocene). [M. 8463.] 2 ao.f., antorbital foramen. h.v., h.v.', impressions of blood-vessels, c., alveolus of canine. e. a.in., external auditory meatus. exo., exoccipital. /./(., frontal horn. f. l.a., foramen lacerum antei'ius. fr., frontal. i. 1-3, incisors or their alveoli. >., jugal. 1., lachrymal. m. 1-3, molars. mes., prenasal bar. 7/1.1’., maxilla. //«., nasal. nar., external nares. n.li., nasal horn. cn.f., orbito-nasal foramen, j/rt., parietal. jxjl., postglenoid process. pi., palatine. 1-4, premolars or their alveoli. pmx., premaxilla. p)-P; paroccij)ital process. pt., pterygoid, y/ty., ]30st-tympanic jirocess. sq., squamosal. st.v., supratemporal ridge. II., optic foramen. CATAL, TERTIARY VERT. FAYUM. PLATE 1 o H g n. CO - A t i PT.A'rE II. Pilge Arsinoitlierium zitfeli, Beadnell ; skull, ])alatal and (1 a) front views; the ends of the horns have been restored : one-third nat. size. Fluvio-marine beds (Upper Eocene). a.o.f., antorbital foramen. ci.p.f., anterior palatine foramen. ho., hasioccipital. hap., ba.sisplienoid. c., canine alveolus. f.a.m., external auditory meatus, t'.i'o., exoccijiital. f.h., frontal born. pi., articirlar surface for mandible. /'. incisors or their alveoli. ui. l-il, molars. UK'S., prenasal bar. m.p.f., maxillo-palatine foramen. [M. 8463.] mx., maxilla. na., nasals. nar., external nares. n.h., nasal horn. orh., orbit. 2^gl., postglenoid process. pi., palatine. pm. 1-4, premolars or their alveoli. pmx., premaxilla. pp f; posterior palatine foramen. jit., pterygoid. jifp; post-tympanic process. CATAI,. TERTIARY VERT FAYUM i^’iATF, II. 'j-MWco dwell'd del etiith. V.I. West,lse'wmaji imp. n.x. *Tt/ o . -- )V.h. - Vp.f- TJb. pgu. 6.a ttl - pty sxo. - mes. pnoc. a.o.f. ' orl ' '777 X. p. mx. ARSINOITHERTUM ZITTELI f M 1 •'1 f ' PLATE III. ]’ig. Page 1. Arsilioitlicrinm zifteli, Beadnell ; three parts grown skull, left side and (1 a) anterior views: oue-sixtli nat. size. Fluvio-marine beds (Upper Eocene). specimen, C. 8130.] - 2. Ditto ; younger skull, superior, (2 a) left lateral, and (2 b) anterior aspects : one-sixth nat. size. Eluvio-marine beds (Upper Eocene). [C. 7805.] 2 cd.c., alispheiioid canal. it.o.f., antorbital i'oranien. ji'gal. la., lachrymal. jii. 1-2, molars. ms.g., me.sethmoid groove. mx., maxilla. na., na.sal. nar., external nare.s. u.li., nasal horn. orb., orbit. pa., parietal. pc^A\\e\\ mandible, upper and (1a) left side views : one-fourth nat. size. Fluvio-inarine beds (Upper Eocene). [M. 8463.] -2 '1. Arsmoitherium midrewsi, Lankester ; left maxilla, outer and (2 a) palatal views : one-fourth nat. size. Fluvio-marine beds (Upper Eocene). [Type specimen, M. 8461.] SO b. Ditto; mandible, upper and (3 a) left lateral views: one-fourth nat. size. Fluvio-marine beds (Upper Eocene). specimen, M. 8461.] 30 (t., angle of mandible. (•., canine, rd., eond}'le. coronoid process. /. 1-3, incisors or their alveoli. 'III. 1-3, molars. m.f., mental foramen. jiiii. 1-4, premolars. a., s\mi[)!iysi.s of mandible. CATAL, TERTIAI^Y VERT. FAYUM PTATK IV. A.H.Searle del.etlitl'i. West, Nerwinaji imp- 1. lA ARSINOITHERIUM ZITTELI. 2.2A3.3^, ARSINOITFIERIUM ANDREV/SL 1 ■1 I v1 9 ■■ , T 0. ■■ 1 1 Tlf f ' '-W /> ■' j T . f'*’- • , T: : ■i^:" 3r , • 1 . ... fil ^Bt * ? - f.' j T' ♦ y... E- .» i'iS ' , AV# ■ill.. ■■ « -A ^ » - r. ,<■ "'. ;„4 a ^ .V- • : 4 ■• , i . «■ / ^ l» • . f‘‘ > .1 r.'Cr ihSi'A- ■ ' ^, Ilf 'It •J,. »» V # ,v A .a ,?v ?.■ ■' ,A ' '-■ >ff PLATE V. I'ig. Page 1. yJrsinoifJ/crittm zilteli, Peadnell ; upper incisor (or canine), crown and (1 a) lateral views : two-tldrds uat. size. Fluvio-marine beds (Upper Eocene). [M. 8470.] 20 2. Ditto; right upper premolar, probably the third, crown view: two-thirds nat. size. Belonging to same individual as last. [M. 8470.] 20 d. Ditto; left upper premolar, probably the second, crown and (3 a) anterior views : two-thirds nat. size. Belonging to same individual as last. [M. 8470.] 20 4. Ditto; left lower molar, crown and (4 a) outer views: two-thirds nat. size. Belonging to same individual as last. [M. 8470.] 23 0. Ditto; left milk-molars 2-4, crown and (5 a) outer views: two-thirds nat. size. Same horizon. [M. 8471.] 21 6. Ditto ; third left upper molar, only (G b) outer views : two-thirds nat, si 7. Ditto; third right ipiper molar, more thirds nat. size. Same horizon. S. Ditto ; right upper molar, greatly woi the latter the roots are shown : two- a.c., anterior column of molars. ae., antero-external cusp. (li., autcro-internal cusp. ((.)■., anterior root. c., cingulum. 0.', postero-internal portion of cingulum. --4, second, third, and fourth milk-molars. )a.r., middle root. slightly worn, crown, (6 a) inner, ze. Same horizon. [M. 8470.] 17 worn than last, crown view : two- [M. 8804.] 17 •n, crown and (8 a) inner views ; in ■thirds nat. size. Same horizon. [M. 8804 a.] 17 ms., mesosfyle. p.C; posterior column of molars. pe., postero-exterual cusp. pi., postero-iiiternal cusp. p.r., posterior root. ps., ])arastyle. a’., inner face of tooth. I I I ! I 1 1 ^"AFAL, 'I'EHTIAAY VEKT FAE'UM /Vl’E V. Wffa, J^evjinaii imT'- A H.Searle del. el lidi. ARSm OITHSRIUM Z IT TPILl. 9 it I '4 i I 4-1 rLA'IE VI. Fig. Pag<> 1. Mcgalolnjrax coc(&)ms, Andrews; premaxilla with incisor teeth, outer and (1a) palatal views: nat. size. Fluvio-tnarine beds (Upper Eocene). [C. 10009.] 03 2. Ditto; right upper maxillary teeth, crown view : nat. size. Same horizon. [Type specimen, M. 8502.] 02 3. >Saf/h(/f}ieriiim mar/num, Andrews; right upper teeth, outer and (3 a) crown views : nat. size. Same horizon. specimen, M. 8398.] 80 4. Ditto; portion of left ramus of mandible with cheek-teeth, upper and (4 a) side views : nat. size. Same horizon. [M. 8868.] 00 b. Sagliatherhun majus, Andrews ; right upper second molar, crown view : nat. size. Same horizon. [C. 10010.] 01 G. S((f/I/afJieriirm antiqmi.m, Andrews & Beadnell ; two right upper nK)lars (in. 2, m. 3), crown view : nat. size. Same horizon. [C. 10057.] SO ac.s., anterior accessory styles, rtc.s.', [losterior accessory styles, antero-external cus]-). e/., aiitero-internal cusp. (•., canine. hs , liypostyle. i. 1-3, incisors or tlieir alveoli. i. F, posterior end of t. 1. m. 1-3, molars. W5., inesostyle. msd., nietastylid. mts., inetastyle. pe. , postero-e.xternal cusji. pf. , postero-internal cusp. i)alatine process of premaxilla pm. 1-4, prmnolars. ps., ])arastyle. talon. : a pP ii; o^ . . i“ H W CM r-H CO ^0 CO § E£i E^ S; O 'Cl, ' .J 'J / PLATE VII. I'ig. Page I. Megalohyrax minor, Andrews ; left upper molars and premolars, crown view ; nat. size. Fliivio-marine beds (Upper Eocene). [Type specimen, C. 8818.] 91 II. Ditto ; right ramus of mandible, inner view and (2 .\) crowns of the cheek- teeth : nat. size. Same horizon. [C. 8822.] 07 3. Ditto ; anterior end of mandible with two incisors, posterior view : nat. size. Same horizon. [C. 8823.] 07 4. Saghatlierium antiquum, Andrews & Beadnell ; right maxilla with cheek- teeth, palatal view : nat. size. Same horizon. ['Type specimen, C. 8635.] 85 5. Ditto; roof of skull, superior view : nat. size. Same horizon. ['fype specimen, C. 8635.] 85 a.e., antero-cxteriial cusp. «.i., aiitero-interiial cusp. f., canine. /)•., frontal. Its., hypostyle. i. 1-2, lirst and second incisors. m. 1-3, molars. ms., rnesost) le. msd., metastylid. mts., iiietastyle. pa., parietal. p.e., postero-external cusp. pt.i., postero-internal cusp ptm. 1-4, premolars. ps., parastyle. so.p., supraorbital process. 1., talon of third lower molar, w Ph g-- LO 'iH I h— t s W H O 2.3. MEGALOHYRAX MINOR. . SAGH.ATHERIUM ANTIQUUM. n i : • PTATE VI I L Fig. Page 1. Mceritherium ItjonsU Andrews; nearly complete sknll of a young individual, upper, (1 a) lower, and (In) posterior views: one-half nat. size. Fluvio- inarine beds (Uppei- Eocene). [C. 7867.] 00 ho., basioccipit.al. c., canine alveolns. cond., exoccipital condyles. e. a.m., external auditory meatus. exo., exoccipitals. f. Lp., foramen lacerum posterius. for., foramina in squamosal. Jr., frontal. f/L, glenoid surface for mandible. 1. 2—3, second and tbird incisors or their alveoli. ju., jugal. »}. 1-3, molars. mx., maxilla. n., nasal. 07-b., orbit. pa., parietal. 2^., palatine. second to fourth premolars. 2>mx., ])remaxilla. p.p., paroccipital process. jdt/., post-tympanic process. ,sor., su])raoccipitah sq., squamosal. CATAI, TERTIARY VKRT.EAYUM IT, ATI-; VI. i prruc Q.Oi.nv olel. et- litK Mintern Bros MCERTTHERIUM LYOR SI r PLATE IX. Pig. Page 1. Mceritherium lyonsi^ Andrews; skull of a young individual, right side view : one-half nat. size. Fluvio-marine beds (Upper Eocene). [C. 7867.] 99 2. Ditto ; right lower dentition, crown view : nat. size. Same horizon. [M. 8501.] 109 3. Ditto; right lower premolars, inner and (3 a) crown views : nat. size. Same horizon. [C. 8127.] 109 4. Ditto ; right upper premolars, crown view : nat. size. Same horizon. [M. 8500.] 10(3 5. Mceritherium trigonoclon, Andrews; right lower molars, crown view : nat. size. [Type specimen, M. 8499.] 128 ae., autero-oxternal cusp. ai., autero-internal cusp. a.o.f., antorbital foramen. e.a.m., external auditory meatus. iwo., exoccipital. fr., frontal. i. 2, second upper incisor. ./it., jugal. m. 1-3, molars. mx., maxilla. na., nasal. unr., external nares. orh., orbit. IM., parietal. pe., postero-external cusp. ^n«.3-4, ])remolars. pmX; premaxilla, juj)., paroccipital process. ])s., parastyle. pty., post-tympanic process. soc., supraoccipital. 6vy., stpiamosal. • •■ 'fi If TK:^' ■Hr IPV-'->.. -zm X w ft VQ C S C s H ft ft > ft ft I— I s ft H ft ft o lu ft ft 1-4. KCERITHERIUM LYOHSI . 5. . ;; TRIGOKODOU >1 T1 « tf f ( I I \ f • r .■ PLA'J'E X. Fig. Page 1. Mceritherium lyonsi, Andrews; left ramus of mandible, witli the molars and prcmolars, upper and (1 a) outer views ; the posterior portion is restored in outline from other specimens : one-half nat. size. Qasr-el-Sa^ha beds (Middle Eocene). [Type specimen, C. 10000.] 108 2. Ditto ; right upper cheek-teeth, crown view ; one-half nat. size. Same horizon. [C. 10001.] IOC 3, Ditto ; anterior portion of skull, side view ; one-half nat. size. Same horizon. [C. 10002.] 99 4. Ditto; posterior portion of the same skull, upper and (4 a) posterior views: one-half nat. size. Same horizon. [C. 10002.] 99 5. Ditto ; crown of last upper molar : one- half nat. size. Same horizon. [M. 8902.] 108 «.o./., antorbital foramen. na., nasals. (•., canine. nar., external nares. (■Olid., condyle of mandible. orb., orbit. cor., eoronoid process. parietal. c.d.m., external auditory meatus. pm. 2-4, premolars. e.co., exoccipital. pmx., premaxilla. i. 1-d, incisors or alveoli of incisors. poe., paroccipital process. HI. l-:3, molars. soc., supraoccipital. m.f., mental foramen. sq., squamosal. CATAL. TERTIARY VERT. FAYUM. PLATE r IS cb MCERITHERTUPI LYONSI. Page <’ig. 1. Moeritherium lyonsi, Andrews; atlas vertebra, posterior, (1a) anterior, and (1b) upper views: one-tliird nat. size. Qasr-el-Sagha beds (Middle Eocene). [M. 8909.J 110 2. Ditto; axis vertebra, anterior and (2 a) lateral views: one-third nat. size. Same horizon. [C. 10059.] 112 3. Ditto ; posterior cervical vertebra, posterior view : one-third nat. size. Same horizon. [M. 8899.] 112 4. Ditto ; dorsal vertebra, associated with type mandible, anterior and (4 a) lateral views : one-third nat. size. Same horizon. [C. 10000.] 112 6. Ditto ; left scapula, outer view : one-third nat. size. Same horizon. [C. 10020.] 117 6. Ditto ; left humerus, posterior and (6 a) anterior views : one-third nat. size. Same horizon. [M. 8931.] 117 7. Ditto ; proximal end of ulna, anterior view : one-third nat. size. Same horizon. [M. 8911.] 118 8. Ditto; right femur, anterior and (8a) posterior views: one-third nat. size. Same horizon. [M. 8932.] 119 9. Ditto; imperfect pelvis, dorsal and (9a) lateral views: one-third nat. size. Same horizon. [M. 8914.] 118 a., acetabulum. a.t., surface for axis, rt.r., anterior zygapopliysis. c., coracoid process. c.h., coracoid border. c./., coronoid fossa (fig. (5 a), capitular facet (fig. 4 a). c.i., crista ilii. cond., condylar facets. tZ., deltoid crest. g.6., glenoid boi’der. (J.C., glenoid cavity. 'j.tr., great trochanter. 7n, head of humerus and femur. li.y., hypapophysis. nc., inner condyle. is., ischium. is.t., ischial tuberosity. Z.A, pit for ligamentum teres, l.tr., lesser trochanter. n.sp., neural spine. 0(Z., odontoid process. 0. f., olecranon fossa. ol., olecranon process. pu., pubis. IKZ., posterior zygapopliysis. }•., surface for radius, s., spine of scapula. 1. f., tubercular facet. t.p., transverse process, i’.c., vertebrarterial canal. CATAL. TERTIARY VERT. FAYUM, PLATE XL MCERITHERIUM LYON SI. i v 4 4 I m I ■ m ..jg PLATE XII. Palceomastodon C?) headnelU, Andrews ; (1 b) posterior views : one-fourth nat. Eocene). al., alisplienoid. al.c, alisplienoid canal. ao.f., antorbital foramen. hitj)., basispheuoiil. e.a.m., external auditory meatus. cu., eustachian opening. exo., exoccipittJ. f.l.a., foramen lacerum anterius. /.?.)»., foramen lacerum medium. fJ.2>; foramen lacerum posterius. f.rn., foramen magnum. f.o., foramen ovale. for., foramina opening into air-sinuses. i.c.c., foramen for internal common carotid. Page skull, lateral, (1 a) palatal, and size. Fluvio-mariue beds (Upper [M. 8464.] 130 ju., jugal. 7n. l-d, molars. mx., maxilla. jw., parietal. 2)1., palatine. 2)m. 2-4, premolars. 2)-2^; paroccipital process. 2'>pf-, posterior palatine foramen. 2>t., pterygoid. 2)t>/., post-tympanic process. S.C., sagittal crest. soc., supraoccipital. sij., squamosal. st.m,, stylomastoid foramen. s.c. C’ATAl,. ThlRTlARY VKRT. FAYUM pCXy. PLATE XII CJCO J ■ Green del.et libK . Minbern Bros imp. pal;t]Omastodoit beadnelli PLATE XIII. . Fnheomastodon (?) beadnelli, Andrews ; anterior portion of yonii" sknll, upper and (1a) side views : three-fourths nat. size; also (1 b) crown view of left upper teeth : nat. size. Fluvio-marine beds (Upper Eocene). [0.8116.] 138 (lo.f., antorbital foramen, frontal, i., incisor. ju., jugal. 7rtc., lachrymal. rni’s.i/., raesethmoid groove. nun. 2-4, milk-molars. m.v., maxilla. 7ia., nasal. nar., external nares. orb., orbit. pah, palate. jnn.v., premaxilla. ^yp., zygomatic process of maxilla CATAI,. Tl' RTIARY VKRT, FAYUM PFATF; XIII n%m- prnx- mm. . 3. ficur'. mrrb riocr. ,v Amt?- { ' ■ -R mm. Z. mm. 4 tnm J. Green del et litK . PALJ^IOMASTODON BEADRELLT Mintern Bros, imp. I f Pae-e 1. Falwomastodon minor, Andrews; portion of ri^ht ramus of mandible, iniernal and (1 a) upper views : nat. size. Fluvio-marine beds (Upper Eocene). [Type specimen, M. 8479 b.] 168 2. Pal(^omasto(Jon[\) headnelli, Km\xe\y?, right upper molars and premolars, crown view : two-thirds nat. size. Same horizon. [M. 8383.] 189 3. Palcromastodon wiiifoni*, Andrews; anterior portion of mandible witli incisors, upper view : one-half nat. size. Same horizon. [M. 8478.] 161 I Wrongly described on Plate as F. leadnelli.] c., incisor. 7n. l-IJ, molars. j>7n. 3-4, premolars. fr/>n., symphysis. Wm f-q H P <^ W m CO c^ CNI 'h V’ ■■ 4 \ 1 I I W ■ v-'- ' TPv-^ T f < t"' t * ■■ PLATE XV. Pig. Pag(? 1. Palwomastodon headnelli, Andrews; left ramus of mandible, upper and (1 a) outer views : one-third nat. size. Fluvio-marine beds (Upper Eocene). specimen, C. 10014.] 150 '1. Ditto ; fragment of left maxilla with greatly worn m. 2 and m. 3, palatal A’iew ; one-third nat. size. Same horizon. [C. 10014 a.] 151 3. Ditto ; atlas vertebra, front view : one-third nat. size. Same horizon. [C. 10060.] 141 lond., surfaces for occipital condyles. i., socket of incisor. VI. l-o, mola.rs. vi.f., mental foramen. vix., maxilla. n.v., neural canal. ii.sjK, neural spine. 0(1., socket for odontoid j)rocess. j>al., palate. ^urt.tf-4, premolars. si/M., symphysis of mandible. I.p., lrans\'erse process. V.C., vertebrarterial canal. zif(j., base of zygomalic process of maxilla. CATAL, TERTIARY VERT. FAYUM. PLATE X/. PAL^OMASTODON BEADNELLI. PLATE XVL Fig. Page 1. Valceomadodon beadneUi, Andrews; axis vertebra, front and (1a) side views: one-sixth nat. size. Fluvio-marine beds (Upper Eocene). [C. 10061.] 144 Ditto ; imperfect right humerus, front and (2 a) back views : one-sixth nat. size. Same horizon. [C. 10013.] 145 3. Ditto ; right femur, front and (3 a) back views : one-sixth nat. size. Same horizon. [C. 10017.] 14G 4. Ditto; left tibia, front and (4a) distal views: one-sixth nat. size. Same horizon. [C. 10015.] 147 c.f., coronoid fos.«a. cn., fuemial crest. d., deltoid crest. g.t; great trochanter. /«., liead. inner articular surface of ujiper end of tibia. J.C., inner condyle. i.m., internal nialleolns. n.sp., neural spine. 0., outer articular surface of upper end of tibia. O.C., outer condyle. o(f., odontoid process. o.f., oleci'anon fossa. sp.r., supinator ridge. t.p., transverse process. O’., trochlear surface of femur. t.t., third trochanter. CATAL. TERTIARY VERT. FAYUM. PLATE X'/l. 1 PAL^OMASTODON BEADNELLI. V B < -i \ I /■ A ’ I a V. V 1 ♦..*:f'.y ( I: X i .' •1 I n » , A ■'> ■ 'I, ) rLATE XVII. 1. MoeritheriuDi (jrdcile, Andrews; anterior portion of skull, palatal view : one- third nat. size. Qasr-el-Sagha beds (Middle Eocene). [Type specimen, C. 10003.] 2. Ditto ; occipital region of same skull, posterior view : one-third nat. size. Same horizon. [i'yp® specimen, C. 10003.] 3. Ditto ; upper molars, side view : one-half nat. size. Same horizon. [M. 8913.] 4. Barf/theriiim grave, Andrews ; left maxilla with teeth, palatal view : one-sixth nat. size. Same horizon. [ specimen, C. 10012.] 5. Ditto ; mandible of same individual, side view : one-sixth nat. size. Same horizon. [Type specimen, C. 10012.] d. Ditto ; third left lower molar of same individual : one-sixth nat. size. Same horizon. [Type specimen, C. 10012.] 7. Ditto; distal portion of left humerus, front and (7 a) back views: one-sixth nat. size. Same horizon. [C. 10012 a.] 8. -Ditto; left radius, front, (8 a) proximal, and (8 b) distal views: oue-sixtli nat. size : belonging to type skeleton. Same borizon. [Type s])ecinien, C. 10012.] 9. Ditto; imperfect right scapula, outer and (9 a) articular surfaces: one-sixth nat. size. Part of the type skeleton. Same horizon. [Type specimen, C. 10012.] c. , alveolus of canine. c.h., coracoid border. c.f; coi'onoid fossa. cor., coronoid process (fig. 5) and coracoid process (lig. !)j. d. , deltoid process. exo., exoccipital. )j.c., glenoid cavity. inner pro.xiinal facet of radius (tig. S .v). i. l-B, incisors. i.c., inner condyle. lu., facet for lunar. m. 1-3, molars. tn.f., mental foi'amen. 7n.v., maxilla. 0., outer proximal facet of radius. 0. C., outer condyle. 01. f., olecranon fossa. 2>l., palatine. Jim. 3—1, premolars. jtm.v., prtiiuaxilla. 2>r., protuberance on mandible. .s., spine of scapula. sc., facet for scaphoid. soc., supraoccij)ital. stj., S(juamosal. s.r., siiiiinator ridge. -.'/.'/■I zygomatic process of maxilla. Page 127 127 128 172 173 174 174 175 174 CATAL. TERTIARY VERT, FAYUM. PLATE CO CD I ! r-i ^ O d MCERITHERIUM GRACILE. BARYTHERIUM GRAVE. 4^^ itt * I I PLATE XVIII. Mg. Page 1. Ancodoti gorrhigei, Andrews & Beadiiell ; mandible, upper and (1 .\) side views: three-fourths nat. size. Fluvio-marine beds (Upper Eocene). [Type specimen, C, 8629.] 179 2. Ditto ; riglit lower molars (m. 2, m. 3), crown view : three-fourths nat. size. Satue horizon. [M, 8428.] 182 3. l)itt(^ ; right upper cheek-teeth, crown view : three-fourths nat. size. Same horizon. [M, 8425.] 181 4. Plnomia serridens, Andrews &; Beadnell ; anterior portion of left ramus of mandible, side and (4a) upper views: three-fourths nat. size. Same horizon. specimen, C. 10007.] 170 5. lihagatherinm ieggptiacum, sp. nov. ; left upper molar, crown view: three- fourths nat. size. Same horizon. [iype specimen, M. 8449.] 192 f., alveolus of canine. com}., condyle of mandible. cor., coronoid process. i. 1-3, incisors or their alveoli. m. 1-3, molars. j)ni. 1-4, premolars. syoi., symphysis of mandible. CATAL. TERTIARY VERT. FAYUM. PLATE XVIII. •K> •ri hJ, • g pq c/I g S ;zi S W q y ^ ^ o q q O H cn E- CD 12; P C o P q o o q o o 2 ^ q p P < A PQ P P I — i lO '■'}A » 1 % I PLATE XIX. 'ig. Page L. Geniohyns minis, Andrews ; symphysis and right rainns of mandible, side and (1 a) upper views: nat. size. Fluvio-marine beds (Upper Eocene). [Type specimen, C. 8634.] 193 2. Ge.mohyns fajumensis, portion of right ramns of mandible with the premolars, side and (2 a) crown views: nat. size. Same horizon. [Type specimen, M. 8435.] 195 3. Vterodon africanns, Andrews ; right ramus of mandible with cheek-teeth, outer view : two-thirds nat. size. Same horizon. [Type specimen, M. 8503.] 220 4. Aiiterodon macrognatlnis, Andrews; right ramus of mandible Avith much- worn and broken teeth, inner view: two-thirds nat. size. Same horizon. [M. 8437 b.] 226 5. Ditto ; two right lower molars [m. 2, m. 3) much abraded, inner view : two- thirds nat. size. Same horizon. [M. 8436.] 226 6. Sinopa efkiopica, sp. nov. ; portion of left ramns of mandible with broken teeth, inner and (6 a) crown views : nat. size. Same horizon. [Type specimen, C. 10193.] 233 7. (I) Apterodon macrogvat/nis, Andrews ; distal end of right humerus, fnmt and (7 a) back views : two-thirds nat. size. Same horizon. [M. 8504.] 231 c., socket of canine. e.f; entepiconclylar foramen. i. 1-3, incisors. i.C; inner condyle. m. 1-3, molars. m.f., mental foramina. ol.f., olecranon fossa, pm. 1-4, premolars. pr., process from lon'cr border of mandible. [id 5 Ph CO p o s mx., premaxilla. soc., supraocci2)ital. Av/., squamosal. -pg., zygomatic process of the scjuamosal. I 'ATAI.,. TERTIARY VERT. EAYUM^ Li. rhcur. mx. nour. pmx. cotuL. West^'Ne'wina.Ti imp G.M.Woodward del.eb libli. PROZEUGLODON ATROX PLATE XXTI. I'ig. Page 1. Crocodiliis articeps, Andrews; anterior portion of sknll from above, (1a) from left side, (1 b) from below : one-third nat. size. Flnvio-marine beds (Upper Eocene). [-^-'yp© specimen, C. 10036,] 261 2. Ditto; mandible from above and (2a) from left side: one-third nat. size. Same horizon. [C. 10065.] 263 utKj., angular. (irt., articular. deni., dentarv. m.c., maxilla, nrt., nasals. orh., orbit. l>cd., palatine. 2>inx., premaxilla, pr./., prefrontal. s.awj., surangular. splenial. tr., transverse bone. I CATAL. 'FKRTIARY W,RT. FAYUM. PI, AT?: xxri I AHS earle.Qe] et West, Newman jmp. pnux/. moo prrbso. rrhOTy. I CROCODILUS ARTICEFS. I •I m t PLATE XXIII. Page 1. Tomistoma africa^tvin, Andrews; mandible from above, (I a) inner side of posterior portion of left ramns, (I b) outer side of posterior portion of right ramus : one-fourth nat. size. Qasr-el-Sagha beds (Middle Eocene). [Type specimen, C. 10006.] 270 2. Ditto; cervical vertebra, from side and (2 a) from back: one-half nat. size. Same horizon. [R. 3332.] 27o o. Tomistoma gavialoides, A\n\xe\v?,-, skull, occipital and (3 a) upper surfaces: one-fourth nat. size. Fluvio-marine beds (Upper Eocene). [Type specimen, C, 8948.] 267 (tnfj., angulai’. (irt., artii-iilar. hoc., basiocfipital. facet i’oi’ head of i-ib. cimd., occipital condyle. (hmt., dentary. i.vo., exocci[)ilal. frontal. Injp., hypapophy.‘' I7l s wM KLk m‘ ’.j . I ■■ • . ' i' ■-> i ■ I ' J.-I ' ■ 'is • i f •”' '^■~J ' - «• ^ *■' .^ ‘ r;'' ilif * ' -■ iT^l I ' : , ^--'KS^ ' *k-' • I '« V. r-V"'' , V ■' v,‘' r \ ■ ■*■.' ‘ <• ■■ ' V' "* ** -V ’ *■•.» ’’ , ., * 'A . li ■ ■•■‘'* ., .i ■ f:' f' •' S: f ^ ■■ ■* " • ■■', ^^■^ ■- Wr'-V i :.\r- l^'" '' if '"V.- i: ?*■■’■ ' 't, -T'. ^ ‘X.'i . '|Mi * " I-'- ' 'J ■ "■;. ■' -.is ^ tjv e • I.j-s"'*’' ■' = . r / T^'. ... - tt"'’’ to ■» Vi 'A \:'C,r'. r-‘, ^.3 Pi^r-ir .y, jT..: teSif,' s '?»! i V [f i, . '. < r e- ■. . ,V'^,;^’.-&® f » . D-'.r vj..-.. ^ r. ' •• ^ * ;* , ■• , _'m* * » ■ -■ :,T ’ ^ if' ^ .~ ' « ' " 3! I 'f- . • ■■’j* J - ■ j’--'.. if . 'sr 3- K' . ■■ y ; ■«' -•■% 'v ” • t I . \ • *■ ..••■'■5 :£i w . ■VXr ^ ^ ^ ; Wk.^ ', ' .i,- ^ ' .'* " / > iV' \ ,7. V ' ^ ' V* ' '( ■* ' . - ■ A^-STk.'*!'? lk >• . ■i^'' «• 'a t.': L v" '• ^ ' •■ ? .i .. ijK.. ■» '^4 PLATE XXIV. 1. Testuflo ammon, Andrews ; shell (probably of a female) from right side, (1 a) from above, (1 b) from below: one-fourth nat. size. Fluvio-marine beds (Upper Eocene). [C. 9240.] ahd., abdoiiiinal sliield. an., anal shield. (Mitoplastral hone. Ep., epiplastral hone. fern., femoral sliield. '/(«., gular shield. hum., humeral .shield. Hy.p., hvoplastral hone. 1 1 I/p. p., hypoplastral hone. n. 1-4, neural (vertebral) shields. K. 1-8, neural hones. nu., nuchal shield, nuchal hone. pect., ])ectoral shield. Ey., pygal hones. A’t/i/i., xiphiplastral hone. CATAI,, TI■■,R'^1ARY VA.RT. KAYUM. Y X i ' / / . i* 4** I •i ^ * T ■ r *j ■ %9 I I V * '/ 4 I \ i / I PLATE XXV. Pig. Page 1. Stereogcnys Andrews ; imperfect skull, from side : nat. size. Qasr-el- Sagha beds (Middle Eocene). [R. 3189.] 295 2. Ditto ; skull, palatal view : nat. size. Same horizon. 3. Ditto ; mandible, from above and (3 a) from nat. size. Same horizon. 4. Thalassochelys lihyca, Andrews ; posterior two-thirds nat. size. Same horizon. ancj., angular process of mandible. art., articular surface of mandible. hoc., basiocci])ital. cor., cormioid process of mandible. ec.pt., eetopferygoid process of pterygoid. e.n., external nares. ep.o., epiotic. e. vo., exoccipital. f., frontal. f. c.i., internal carotid foramen. f.s., foramen sphenoidale. . ^ " iN> m-H-I -I .'^•' II •, ,, p„v; ---’^K '' ‘ >'■ .’ '• ,.■ i’i J*', JT i.’*: